What do you call a linked list where every node has a pointer to the successor and predecessor?

Complex Linked List Implementation

The implementation we have learnt till now is Singly Linked List as it contains only link to a single successor. But there are also other complex linked list implementation in data structure.

Complex linked list implementation consists of three important implementations, i.e. the circularly linked list, the doubly linked list, and the multilinked list.

We wil discuss each of them now. Let’s learn about the first type, i.e. Circularly Linked List.

Circularly Linked List

In a circularly linked list, the points of the last node is linked to the first node of the list. They are mainly used in such list that allows access to the middle nodes of the list without starting at the beginning.

What do you call a linked list where every node has a pointer to the successor and predecessor?

Doubly-linked list:

What do you call a linked list where every node has a pointer to the successor and predecessor?

Linked List Types in Data Structure

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Inorder Successor in Binary Search Tree

In Binary Tree, Inorder successor of a node is the next node in Inorder traversal of the Binary Tree. Inorder Successor is NULL for the last node in Inorder traversal.

In Binary Search Tree, Inorder Successor of an input node can also be defined as the node with the smallest key greater than the key of the input node. So, it is sometimes important to find next node in sorted order.

In the above diagram, inorder successor of 8 is 10, inorder successor of 10 is 12 and inorder successor of 14 is 20.

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

Method 1 (Uses Parent Pointer)
In this method, we assume that every node has a parent pointer.
The Algorithm is divided into two cases on the basis of the right subtree of the input node being empty or not.



Input: node, root // node is the node whose Inorder successor is needed.
Output: succ // succ is Inorder successor of node.

  1. If right subtree of node is not NULL, then succ lies in right subtree. Do the following.
    Go to right subtree and return the node with minimum key value in the right subtree.
  2. If right subtree of node is NULL, then succ is one of the ancestors. Do the following.
    Travel up using the parent pointer until you see a node which is left child of its parent. The parent of such a node is the succ.

Implementation:
Note that the function to find InOrder Successor is highlighted (with gray background) in below code.




#include <iostream>
using namespace std;
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
struct node {
int data;
struct node* left;
struct node* right;
struct node* parent;
};
struct node* minValue(struct node* node);
struct node* inOrderSuccessor(
struct node* root,
struct node* n)
{
// step 1 of the above algorithm
if (n->right != NULL)
return minValue(n->right);
// step 2 of the above algorithm
struct node* p = n->parent;
while (p != NULL && n == p->right) {
n = p;
p = p->parent;
}
return p;
}
/* Given a non-empty binary search tree,
return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
struct node* minValue(struct node* node)
{
struct node* current = node;
/* loop down to find the leftmost leaf */
while (current->left != NULL) {
current = current->left;
}
return current;
}
/* Helper function that allocates a new
node with the given data and
NULL left and right pointers. */
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(
struct node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->parent = NULL;
return (node);
}
/* Give a binary search tree and
a number, inserts a new node with
the given number in the correct
place in the tree. Returns the new
root pointer which the caller should
then use (the standard trick to
avoid using reference parameters). */
struct node* insert(struct node* node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == NULL)
return (newNode(data));
else {
struct node* temp;
/* 2. Otherwise, recur down the tree */
if (data <= node->data) {
temp = insert(node->left, data);
node->left = temp;
temp->parent = node;
}
else {
temp = insert(node->right, data);
node->right = temp;
temp->parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
/* Driver program to test above functions*/
int main()
{
struct node *root = NULL, *temp, *succ, *min;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root->left->right->right;
succ = inOrderSuccessor(root, temp);
if (succ != NULL)
cout << "\n Inorder Successor of " << temp->data<< " is "<< succ->data;
else
cout <<"\n Inorder Successor doesn't exit";
getchar();
return 0;
}
// this code is contributed by shivanisinghss2110




#include <stdio.h>
#include <stdlib.h>
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
struct node {
int data;
struct node* left;
struct node* right;
struct node* parent;
};
struct node* minValue(struct node* node);
struct node* inOrderSuccessor(
struct node* root,
struct node* n)
{
// step 1 of the above algorithm
if (n->right != NULL)
return minValue(n->right);
// step 2 of the above algorithm
struct node* p = n->parent;
while (p != NULL && n == p->right) {
n = p;
p = p->parent;
}
return p;
}
/* Given a non-empty binary search tree,
return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
struct node* minValue(struct node* node)
{
struct node* current = node;
/* loop down to find the leftmost leaf */
while (current->left != NULL) {
current = current->left;
}
return current;
}
/* Helper function that allocates a new
node with the given data and
NULL left and right pointers. */
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(
struct node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->parent = NULL;
return (node);
}
/* Give a binary search tree and
a number, inserts a new node with
the given number in the correct
place in the tree. Returns the new
root pointer which the caller should
then use (the standard trick to
avoid using reference parameters). */
struct node* insert(struct node* node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == NULL)
return (newNode(data));
else {
struct node* temp;
/* 2. Otherwise, recur down the tree */
if (data <= node->data) {
temp = insert(node->left, data);
node->left = temp;
temp->parent = node;
}
else {
temp = insert(node->right, data);
node->right = temp;
temp->parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
/* Driver program to test above functions*/
int main()
{
struct node *root = NULL, *temp, *succ, *min;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root->left->right->right;
succ = inOrderSuccessor(root, temp);
if (succ != NULL)
printf(
"\n Inorder Successor of %d is %d ",
temp->data, succ->data);
else
printf("\n Inorder Successor doesn't exit");
getchar();
return 0;
}




// Java program to find minimum
// value node in Binary Search Tree
// A binary tree node
class Node {
int data;
Node left, right, parent;
Node(int d)
{
data = d;
left = right = parent = null;
}
}
class BinaryTree {
static Node head;
/* Given a binary search tree and a number,
inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
Node insert(Node node, int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == null) {
return (new Node(data));
}
else {
Node temp = null;
/* 2. Otherwise, recur down the tree */
if (data <= node.data) {
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
}
else {
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
Node inOrderSuccessor(Node root, Node n)
{
// step 1 of the above algorithm
if (n.right != null) {
return minValue(n.right);
}
// step 2 of the above algorithm
Node p = n.parent;
while (p != null && n == p.right) {
n = p;
p = p.parent;
}
return p;
}
/* Given a non-empty binary search
tree, return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
Node minValue(Node node)
{
Node current = node;
/* loop down to find the leftmost leaf */
while (current.left != null) {
current = current.left;
}
return current;
}
// Driver program to test above functions
public static void main(String[] args)
{
BinaryTree tree = new BinaryTree();
Node root = null, temp = null, suc = null, min = null;
root = tree.insert(root, 20);
root = tree.insert(root, 8);
root = tree.insert(root, 22);
root = tree.insert(root, 4);
root = tree.insert(root, 12);
root = tree.insert(root, 10);
root = tree.insert(root, 14);
temp = root.left.right.right;
suc = tree.inOrderSuccessor(root, temp);
if (suc != null) {
System.out.println(
"Inorder successor of "
+ temp.data + " is " + suc.data);
}
else {
System.out.println(
"Inorder successor does not exist");
}
}
}
// This code has been contributed by Mayank Jaiswal




# Python program to find the inorder successor in a BST
# A binary tree node
class Node:
# Constructor to create a new node
def __init__(self, key):
self.data = key
self.left = None
self.right = None
def inOrderSuccessor(n):
# Step 1 of the above algorithm
if n.right is not None:
return minValue(n.right)
# Step 2 of the above algorithm
p = n.parent
while( p is not None):
if n != p.right :
break
n = p
p = p.parent
return p
# Given a non-empty binary search tree, return the
# minimum data value found in that tree. Note that the
# entire tree doesn't need to be searched
def minValue(node):
current = node
# loop down to find the leftmost leaf
while(current is not None):
if current.left is None:
break
current = current.left
return current
# Given a binary search tree and a number, inserts a
# new node with the given number in the correct place
# in the tree. Returns the new root pointer which the
# caller should then use( the standard trick to avoid
# using reference parameters)
def insert( node, data):
# 1) If tree is empty then return a new singly node
if node is None:
return Node(data)
else:
# 2) Otherwise, recur down the tree
if data <= node.data:
temp = insert(node.left, data)
node.left = temp
temp.parent = node
else:
temp = insert(node.right, data)
node.right = temp
temp.parent = node
# return the unchanged node pointer
return node
# Driver program to test above function
root = None
# Creating the tree given in the above diagram
root = insert(root, 20)
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right
succ = inOrderSuccessor(temp)
if succ is not None:
print ("\nInorder Successor of % d is % d "%(temp.data, succ.data))
else:
print ("\nInorder Successor doesn't exist")
# This code is contributed by Nikhil Kumar Singh(nickzuck_007)




// C# program to find minimum
// value node in Binary Search Tree
using System;
// A binary tree node
public
class Node
{
public
int data;
public
Node left, right, parent;
public
Node(int d)
{
data = d;
left = right = parent = null;
}
}
public class BinaryTree
{
static Node head;
/* Given a binary search tree and a number,
inserts a new node with the given number in
the correct place in the tree. Returns the new
root pointer which the caller should then use
(the standard trick to avoid using reference
parameters). */
Node insert(Node node, int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == null)
{
return (new Node(data));
}
else
{
Node temp = null;
/* 2. Otherwise, recur down the tree */
if (data <= node.data)
{
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
}
else
{
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
Node inOrderSuccessor(Node root, Node n)
{
// step 1 of the above algorithm
if (n.right != null)
{
return minValue(n.right);
}
// step 2 of the above algorithm
Node p = n.parent;
while (p != null && n == p.right)
{
n = p;
p = p.parent;
}
return p;
}
/* Given a non-empty binary search
tree, return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
Node minValue(Node node)
{
Node current = node;
/* loop down to find the leftmost leaf */
while (current.left != null)
{
current = current.left;
}
return current;
}
// Driver program to test above functions
public static void Main(String[] args)
{
BinaryTree tree = new BinaryTree();
Node root = null, temp = null, suc = null, min = null;
root = tree.insert(root, 20);
root = tree.insert(root, 8);
root = tree.insert(root, 22);
root = tree.insert(root, 4);
root = tree.insert(root, 12);
root = tree.insert(root, 10);
root = tree.insert(root, 14);
temp = root.left.right.right;
suc = tree.inOrderSuccessor(root, temp);
if (suc != null) {
Console.WriteLine(
"Inorder successor of "
+ temp.data + " is " + suc.data);
}
else {
Console.WriteLine(
"Inorder successor does not exist");
}
}
}
// This code is contributed by aashish2995




<script>
// JavaScript program to find minimum
// value node in Binary Search Tree
// A binary tree node
class Node {
constructor(val) {
this.data = val;
this.left = null;
this.right = null;
this.parent = null;
}
}
var head;
/*
* Given a binary search tree and a number,
inserts a new node with the given
* number in the correct place in the tree.
Returns the new root pointer which
* the caller should then use
(the standard trick to afunction using reference
* parameters).
*/
function insert(node , data) {
/*
* 1. If the tree is empty,
return a new, single node
*/
if (node == null) {
return (new Node(data));
} else {
var temp = null;
/* 2. Otherwise, recur down the tree */
if (data <= node.data) {
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
} else {
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
function inOrderSuccessor(root, n) {
// step 1 of the above algorithm
if (n.right != null) {
return minValue(n.right);
}
// step 2 of the above algorithm
var p = n.parent;
while (p != null && n == p.right) {
n = p;
p = p.parent;
}
return p;
}
/*
* Given a non-empty binary search tree,
return the minimum data value found in
* that tree. Note that the entire tree
does not need to be searched.
*/
function minValue(node) {
var current = node;
/* loop down to find the leftmost leaf */
while (current.left != null) {
current = current.left;
}
return current;
}
// Driver program to test above functions
var root = null, temp = null,
suc = null, min = null;
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
suc = inOrderSuccessor(root, temp);
if (suc != null) {
document.write("Inorder successor of " +
temp.data + " is " + suc.data);
} else {
document.write(
"Inorder successor does not exist"
);
}
// This code contributed by gauravrajput1
</script>
Output Inorder Successor of 14 is 20

Complexity Analysis:

  • Time Complexity: O(h), where h is the height of the tree.
    As in the second case(suppose skewed tree) we have to travel all the way towards the root.
  • Auxiliary Space: O(1).
    Due to no use of any data structure for storing values.

Method 2 (Search from root)
Parent pointer is NOT needed in this algorithm. The Algorithm is divided into two cases on the basis of right subtree of the input node being empty or not.

Input: node, root // node is the node whose Inorder successor is needed.

Output: succ // succ is Inorder successor of node.

  1. If right subtree of node is not NULL, then succ lies in right subtree. Do the following.
    Go to right subtree and return the node with minimum key value in the right subtree.
  2. If right subtree of node is NULL, then start from the root and use search-like technique. Do the following.
    Travel down the tree, if a node’s data is greater than root’s data then go right side, otherwise, go to left side.

Below is the implementation of the above approach:




// C++ program for above approach
#include <iostream>
using namespace std;
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
struct node* parent;
};
struct node* minValue(struct node* node);
struct node* inOrderSuccessor(struct node* root,
struct node* n)
{
// Step 1 of the above algorithm
if (n->right != NULL)
return minValue(n->right);
struct node* succ = NULL;
// Start from root and search for
// successor down the tree
while (root != NULL)
{
if (n->data < root->data)
{
succ = root;
root = root->left;
}
else if (n->data > root->data)
root = root->right;
else
break;
}
return succ;
}
// Given a non-empty binary search tree,
// return the minimum data value found
// in that tree. Note that the entire
// tree does not need to be searched.
struct node* minValue(struct node* node)
{
struct node* current = node;
// Loop down to find the leftmost leaf
while (current->left != NULL)
{
current = current->left;
}
return current;
}
// Helper function that allocates a new
// node with the given data and NULL left
// and right pointers.
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(struct node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->parent = NULL;
return (node);
}
// Give a binary search tree and a
// number, inserts a new node with
// the given number in the correct
// place in the tree. Returns the new
// root pointer which the caller should
// then use (the standard trick to
// avoid using reference parameters).
struct node* insert(struct node* node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == NULL)
return (newNode(data));
else
{
struct node* temp;
/* 2. Otherwise, recur down the tree */
if (data <= node->data)
{
temp = insert(node->left, data);
node->left = temp;
temp->parent = node;
}
else
{
temp = insert(node->right, data);
node->right = temp;
temp->parent = node;
}
/* Return the (unchanged) node pointer */
return node;
}
}
// Driver code
int main()
{
struct node *root = NULL, *temp, *succ, *min;
// Creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root->left->right->right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != NULL)
cout << "\n Inorder Successor of "
<< temp->data << " is "<< succ->data;
else
cout <<"\n Inorder Successor doesn't exit";
getchar();
return 0;
}
// This code is contributed by shivanisinghss2110




// C program for above approach
#include <stdio.h>
#include <stdlib.h>
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
struct node* parent;
};
struct node* minValue(struct node* node);
struct node* inOrderSuccessor(
struct node* root,
struct node* n)
{
// step 1 of the above algorithm
if (n->right != NULL)
return minValue(n->right);
struct node* succ = NULL;
// Start from root and search for
// successor down the tree
while (root != NULL)
{
if (n->data < root->data)
{
succ = root;
root = root->left;
}
else if (n->data > root->data)
root = root->right;
else
break;
}
return succ;
}
/* Given a non-empty binary search tree,
return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
struct node* minValue(struct node* node)
{
struct node* current = node;
/* loop down to find the leftmost leaf */
while (current->left != NULL)
{
current = current->left;
}
return current;
}
/* Helper function that allocates a new
node with the given data and
NULL left and right pointers. */
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(
struct node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->parent = NULL;
return (node);
}
/* Give a binary search tree and
a number, inserts a new node with
the given number in the correct
place in the tree. Returns the new
root pointer which the caller should
then use (the standard trick to
avoid using reference parameters). */
struct node* insert(struct node* node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == NULL)
return (newNode(data));
else
{
struct node* temp;
/* 2. Otherwise, recur down the tree */
if (data <= node->data)
{
temp = insert(node->left, data);
node->left = temp;
temp->parent = node;
}
else
{
temp = insert(node->right, data);
node->right = temp;
temp->parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
/* Driver program to test above functions*/
int main()
{
struct node *root = NULL, *temp, *succ, *min;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root->left->right->right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != NULL)
printf(
"\n Inorder Successor of %d is %d ",
temp->data, succ->data);
else
printf("\n Inorder Successor doesn't exit");
getchar();
return 0;
}
// Thanks to R.Srinivasan for suggesting this method.




// Java program for above approach
class GFG
{
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
static class node
{
int data;
node left;
node right;
node parent;
};
static node inOrderSuccessor(
node root,
node n)
{
// step 1 of the above algorithm
if (n.right != null)
return minValue(n.right);
node succ = null;
// Start from root and search for
// successor down the tree
while (root != null)
{
if (n.data < root.data)
{
succ = root;
root = root.left;
}
else if (n.data > root.data)
root = root.right;
else
break;
}
return succ;
}
/* Given a non-empty binary search tree,
return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
static node minValue(node node)
{
node current = node;
/* loop down to find the leftmost leaf */
while (current.left != null)
{
current = current.left;
}
return current;
}
/* Helper function that allocates a new
node with the given data and
null left and right pointers. */
static node newNode(int data)
{
node node = new node();
node.data = data;
node.left = null;
node.right = null;
node.parent = null;
return (node);
}
/* Give a binary search tree and
a number, inserts a new node with
the given number in the correct
place in the tree. Returns the new
root pointer which the caller should
then use (the standard trick to
astatic void using reference parameters). */
static node insert(node node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == null)
return (newNode(data));
else
{
node temp;
/* 2. Otherwise, recur down the tree */
if (data <= node.data)
{
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
}
else
{
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
/* Driver program to test above functions*/
public static void main(String[] args)
{
node root = null, temp, succ, min;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != null)
System.out.printf(
"\n Inorder Successor of %d is %d ",
temp.data, succ.data);
else
System.out.printf("\n Inorder Successor doesn't exit");
}
}
// This code is contributed by gauravrajput1




# Python program to find
# the inorder successor in a BST
# A binary tree node
class Node:
# Constructor to create a new node
def __init__(self, key):
self.data = key
self.left = None
self.right = None
def inOrderSuccessor(root, n):
# Step 1 of the above algorithm
if n.right is not None:
return minValue(n.right)
# Step 2 of the above algorithm
succ=Node(None)
while( root):
if(root.data<n.data):
root=root.right
elif(root.data>n.data):
succ=root
root=root.left
else:
break
return succ
# Given a non-empty binary search tree,
# return the minimum data value
# found in that tree. Note that the
# entire tree doesn't need to be searched
def minValue(node):
current = node
# loop down to find the leftmost leaf
while(current is not None):
if current.left is None:
break
current = current.left
return current
# Given a binary search tree
# and a number, inserts a
# new node with the given
# number in the correct place
# in the tree. Returns the
# new root pointer which the
# caller should then use
# (the standard trick to avoid
# using reference parameters)
def insert( node, data):
# 1) If tree is empty
# then return a new singly node
if node is None:
return Node(data)
else:
# 2) Otherwise, recur down the tree
if data <= node.data:
temp = insert(node.left, data)
node.left = temp
temp.parent = node
else:
temp = insert(node.right, data)
node.right = temp
temp.parent = node
# return the unchanged node pointer
return node
# Driver program to test above function
if __name__ == "__main__":
root = None
# Creating the tree given in the above diagram
root = insert(root, 20)
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right
succ = inOrderSuccessor( root, temp)
if succ is not None:
print("Inorder Successor of" ,
temp.data ,"is" ,succ.data)
else:
print("InInorder Successor doesn't exist")




// C# program for above approach
using System;
public class GFG
{
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
public
class node
{
public
int data;
public
node left;
public
node right;
public
node parent;
};
static node inOrderSuccessor(
node root,
node n)
{
// step 1 of the above algorithm
if (n.right != null)
return minValue(n.right);
node succ = null;
// Start from root and search for
// successor down the tree
while (root != null)
{
if (n.data < root.data)
{
succ = root;
root = root.left;
}
else if (n.data > root.data)
root = root.right;
else
break;
}
return succ;
}
/* Given a non-empty binary search tree,
return the minimum data
value found in that tree. Note that
the entire tree does not need
to be searched. */
static node minValue(node node)
{
node current = node;
/* loop down to find the leftmost leaf */
while (current.left != null)
{
current = current.left;
}
return current;
}
/* Helper function that allocates a new
node with the given data and
null left and right pointers. */
static node newNode(int data)
{
node node = new node();
node.data = data;
node.left = null;
node.right = null;
node.parent = null;
return (node);
}
/* Give a binary search tree and
a number, inserts a new node with
the given number in the correct
place in the tree. Returns the new
root pointer which the caller should
then use (the standard trick to
astatic void using reference parameters). */
static node insert(node node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == null)
return (newNode(data));
else
{
node temp;
/* 2. Otherwise, recur down the tree */
if (data <= node.data)
{
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
}
else
{
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
/* Driver program to test above functions*/
public static void Main(String[] args)
{
node root = null, temp, succ;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != null)
Console.Write(
"\n Inorder Successor of {0} is {1} ",
temp.data, succ.data);
else
Console.Write("\n Inorder Successor doesn't exit");
}
}
// This code is contributed by gauravrajput1




<script>
class Node
{
constructor(data)
{
this.data=data;;
this.left=this.right=this.parent=null;
}
}
function inOrderSuccessor(root,n)
{
// step 1 of the above algorithm
if (n.right != null)
return minValue(n.right);
let succ = null;
// Start from root and search for
// successor down the tree
while (root != null)
{
if (n.data < root.data)
{
succ = root;
root = root.left;
}
else if (n.data > root.data)
root = root.right;
else
break;
}
return succ;
}
function minValue(node)
{
let current = node;
/* loop down to find the leftmost leaf */
while (current.left != null)
{
current = current.left;
}
return current;
}
function insert(node,data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == null)
return (new Node(data));
else
{
let temp;
/* 2. Otherwise, recur down the tree */
if (data <= node.data)
{
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
}
else
{
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* return the (unchanged) node pointer */
return node;
}
}
let root = null, temp, succ, min;
// creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != null)
document.write(
"<br> Inorder Successor of "+temp.data+" is "+
succ.data);
else
document.write("<br> Inorder Successor doesn't exit");
// This code is contributed by unknown2108
</script>
Output Inorder Successor of 14 is 20

Complexity Analysis:

  • Time Complexity: O(h), where h is the height of the tree.
    In the worst case as explained above we travel the whole height of the tree
  • Auxiliary Space: O(1).
    Due to no use of any data structure for storing values.

Method 3 (Inorder traversal)An inorder transversal of BST produces a sorted sequence. Therefore, we perform an inorder traversal. The first encountered node with value greater than the node is the inorder successor.

Input: node, root // node is the node whose ignorer successor is needed.
Output: succ // succ is Inorder successor of node.

Below is the implementation of the above approach:




// C++ program for above approach
#include <iostream>
using namespace std;
/* A binary tree node has data,
the pointer to left child
and a pointer to right child */
struct node
{
int data;
struct node* left;
struct node* right;
struct node* parent;
};
struct node* newNode(int data);
void inOrderTraversal(struct node* root,
struct node* n,
struct node* succ)
{
if(root==nullptr) { return; }
inOrderTraversal(root->left, n, succ);
if(root->data>n->data && !succ->left) { succ->left = root; return; }
inOrderTraversal(root->right, n, succ);
}
struct node* inOrderSuccessor(struct node* root,
struct node* n)
{
struct node* succ = newNode(0);
inOrderTraversal(root, n, succ);
return succ->left;
}
// Helper function that allocates a new
// node with the given data and NULL left
// and right pointers.
struct node* newNode(int data)
{
struct node* node = (struct node*)
malloc(sizeof(struct node));
node->data = data;
node->left = NULL;
node->right = NULL;
node->parent = NULL;
return (node);
}
// Give a binary search tree and a
// number, inserts a new node with
// the given number in the correct
// place in the tree. Returns the new
// root pointer which the caller should
// then use (the standard trick to
// avoid using reference parameters).
struct node* insert(struct node* node,
int data)
{
/* 1. If the tree is empty, return a new,
single node */
if (node == NULL)
return (newNode(data));
else
{
struct node* temp;
/* 2. Otherwise, recur down the tree */
if (data <= node->data)
{
temp = insert(node->left, data);
node->left = temp;
temp->parent = node;
}
else
{
temp = insert(node->right, data);
node->right = temp;
temp->parent = node;
}
/* Return the (unchanged) node pointer */
return node;
}
}
// Driver code
int main()
{
struct node *root = NULL, *temp, *succ, *min;
// Creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root->left->right->right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != NULL)
cout << "\n Inorder Successor of "
<< temp->data << " is "<< succ->data;
else
cout <<"\n Inorder Successor doesn't exist";
//getchar();
return 0;
}
// This code is contributed by jaisw7




// Java program for above approach
import java.util.*;
class GFG {
/*
* A binary tree node has data, the pointer to left child and a pointer to right
* child
*/
static class node {
int data;
node left;
node right;
node parent;
};
static void inOrderTraversal(node root) {
if (root == null) {
return;
}
inOrderTraversal(root.left);
System.out.print(root.data);
inOrderTraversal(root.right);
}
static void inOrderTraversal(node root, node n, node succ) {
if (root == null) {
return;
}
inOrderTraversal(root.left, n, succ);
if (root.data > n.data && succ.left == null) {
succ.left = root;
return;
}
inOrderTraversal(root.right, n, succ);
}
static node inOrderSuccessor(node root, node n) {
node succ = newNode(0);
inOrderTraversal(root, n, succ);
return succ.left;
}
// Helper function that allocates a new
// node with the given data and null left
// and right pointers.
static node newNode(int data) {
node node = new node();
node.data = data;
node.left = null;
node.right = null;
node.parent = null;
return (node);
}
// Give a binary search tree and a
// number, inserts a new node with
// the given number in the correct
// place in the tree. Returns the new
// root pointer which the caller should
// then use (the standard trick to
// astatic void using reference parameters).
static node insert(node node, int data) {
/*
* 1. If the tree is empty, return a new, single node
*/
if (node == null)
return (newNode(data));
else {
node temp;
/* 2. Otherwise, recur down the tree */
if (data <= node.data) {
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
} else {
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* Return the (unchanged) node pointer */
return node;
}
}
// Driver code
public static void main(String[] args) {
node root = null, temp, succ, min;
// Creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != null)
System.out.print("\n Inorder Successor of " + temp.data + " is " + succ.data);
else
System.out.print("\n Inorder Successor doesn't exist");
}
}
// This code is contributed by Rajput-Ji




// C# program for above approach
using System;
using System.Collections.Generic;
public class GFG {
/*
* A binary tree node has data, the pointer to left child and a pointer to right
* child
*/
public class node {
public int data;
public node left;
public node right;
public node parent;
};
static void inOrderTraversal(node root) {
if (root == null) {
return;
}
inOrderTraversal(root.left);
Console.Write(root.data);
inOrderTraversal(root.right);
}
static void inOrderTraversal(node root, node n, node succ) {
if (root == null) {
return;
}
inOrderTraversal(root.left, n, succ);
if (root.data > n.data && succ.left == null) {
succ.left = root;
return;
}
inOrderTraversal(root.right, n, succ);
}
static node inOrderSuccessor(node root, node n) {
node succ = newNode(0);
inOrderTraversal(root, n, succ);
return succ.left;
}
// Helper function that allocates a new
// node with the given data and null left
// and right pointers.
static node newNode(int data) {
node node = new node();
node.data = data;
node.left = null;
node.right = null;
node.parent = null;
return (node);
}
// Give a binary search tree and a
// number, inserts a new node with
// the given number in the correct
// place in the tree. Returns the new
// root pointer which the caller should
// then use (the standard trick to
// astatic void using reference parameters).
static node insert(node node, int data) {
/*
* 1. If the tree is empty, return a new, single node
*/
if (node == null)
return (newNode(data));
else {
node temp;
/* 2. Otherwise, recur down the tree */
if (data <= node.data) {
temp = insert(node.left, data);
node.left = temp;
temp.parent = node;
} else {
temp = insert(node.right, data);
node.right = temp;
temp.parent = node;
}
/* Return the (unchanged) node pointer */
return node;
}
}
// Driver code
public static void Main(String[] args) {
node root = null, temp, succ, min;
// Creating the tree given in the above diagram
root = insert(root, 20);
root = insert(root, 8);
root = insert(root, 22);
root = insert(root, 4);
root = insert(root, 12);
root = insert(root, 10);
root = insert(root, 14);
temp = root.left.right.right;
// Function Call
succ = inOrderSuccessor(root, temp);
if (succ != null)
Console.Write("\n Inorder Successor of " + temp.data + " is " + succ.data);
else
Console.Write("\n Inorder Successor doesn't exist");
}
}
// This code contributed by Rajput-Ji
Output Inorder Successor of 14 is 20

Complexity Analysis:

Time Complexity: O(h), where h is the height of the tree.In the worst case as explained above we travel the whole height of the tree
Auxiliary Space: O(1).Due to no use of any data structure for storing values.

&list=PLqM7alHXFySHCXD7r1J0ky9Zg_GBB1dbk

References:
http://net.pku.edu.cn/~course/cs101/2007/resource/Intro2Algorithm/book6/chap13.htm
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

What do you call a linked list where every node has a pointer to the successor and predecessor?




Article Tags :
Binary Search Tree
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Morgan Stanley
Practice Tags :
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  • Last Updated : 29 Sep, 2020

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