Given a linked list. The task is to print the difference between the first odd-positioned node with the sum of all other odd-positioned nodes.
Examples:
Input : 1 -> 8 -> 3 -> 10 -> 17 -> 22 -> 29 -> 42
Output : -48
Alternate nodes : 1 -> 3 -> 17 -> 29
1 – (3 + 17 + 29) = -48Input : 10 -> 17 -> 33 -> 38 -> 73
Output : -96
Alternate nodes : 10 -> 33 -> 73
10 – (33 + 73) = -96
We have already discussed the sum of the alternative nodes of a linked list
Iterative Approach :
- Traverse the whole linked list.
- Set difference = 0 and count=0.
- Subtract the data of node from difference when count is even.
- Visit the next node.
Below is the implementation of the above approach:
C++
// C++ program to print the difference // of Alternate Nodes #include <bits/stdc++.h>using namespace std;// Link list node struct Node { int data; struct Node* next; }; // Function to get the alternate // nodes of the linked list int subtractAlternateNode(struct Node* head) { int count = 0; int difference = 0; while (head != NULL) { // When count is even subtract the nodes if (count % 2 == 0) if (difference == 0){ difference = head->data; } else{ difference -= head->data; } // Count the nodes count++; // Move on the next node. head = head->next; } return difference; } // Function to push node at head void push(struct Node** head_ref, int new_data) { struct Node* new_node = new Node; new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node; } // Driver code int main() { // Start with the empty list struct Node* head = NULL; // Use push() function to construct // the below list 8 -> 23 -> 11 -> 29 -> 12 push(&head, 12); push(&head, 29); push(&head, 11); push(&head, 23); push(&head, 8); cout << subtractAlternateNode(head); return 0; }// This code is contributed by shubhamsingh10 |
C
// C program to print the difference // of Alternate Nodes #include <stdio.h> #include <stdlib.h> // Link list node struct Node { int data; struct Node* next; }; // Function to get the alternate // nodes of the linked list int subtractAlternateNode(struct Node* head) { int count = 0; int difference = 0; while (head != NULL) { // When count is even subtract the nodes if (count % 2 == 0) if (difference == 0){ difference = head->data; } else{ difference -= head->data; } // Count the nodes count++; // Move on the next node. head = head->next; } return difference; } // Function to push node at head void push(struct Node** head_ref, int new_data) { struct Node* new_node = (struct Node* )malloc(sizeof(struct Node)); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node; } // Driver code int main() { // Start with the empty list struct Node* head = NULL; // Use push() function to construct // the below list 8 -> 23 -> 11 -> 29 -> 12 push(&head, 12); push(&head, 29); push(&head, 11); push(&head, 23); push(&head, 8); printf(" %d ", subtractAlternateNode(head)); return 0; } |
Java
// Java program to print the difference // of Alternate Nodes import java.util.*;class GFG { static Node head;// Link list node static class Node { int data; Node next; }; // Function to get the alternate // nodes of the linked list static int subtractAlternateNode(Node head) { int count = 0; int difference = 0; while (head != null) { // When count is even subtract the nodes if (count % 2 == 0) if (difference == 0) { difference = head.data; } else { difference -= head.data; } // Count the nodes count++; // Move on the next node. head = head.next; } return difference; } // Function to push node at head static void push(Node head_ref, int new_data) { Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref;} // Driver code public static void main(String[] args) { // Start with the empty list head = null; // Use push() function to con // the below list 8 . 23 . 11 . 29 . 12 push(head, 12); push(head, 29); push(head, 11); push(head, 23); push(head, 8); System.out.printf(" %d ", subtractAlternateNode(head));}}// This code is contributed by Princi Singh |
Python3
# Python3 program to print the difference # of Alternate Nodes import math # Link list node class Node: def __init__(self, data): self.data = data self.next = None# Function to get the alternate # nodes of the linked list def subtractAlternateNode(head): count = 0 difference = 0 while (head != None) : # When count is even subtract the nodes if (count % 2 == 0): if (difference == 0): difference = head.data else: difference = difference - head.data # Count the nodes count = count + 1 # Move on the next node. head = head.next return difference # Function to push node at head def push(head_ref, new_data): new_node = Node(new_data) new_node.data = new_data new_node.next = head_ref head_ref = new_node return head_ref# Driver code if __name__=='__main__': # Start with the empty list head = None # Use head=push() function to construct # the below list 8 . 23 . 11 . 29 . 12 head = push(head, 12) head = push(head, 29) head = push(head, 11) head = push(head, 23) head = push(head, 8) print(subtractAlternateNode(head)) # This code is contributed by Srathore |
C#
// C# program to print the difference // of Alternate Nodes using System; class GFG { static Node head;// Link list node public class Node { public int data; public Node next; }; // Function to get the alternate // nodes of the linked list static int subtractAlternateNode(Node head) { int count = 0; int difference = 0; while (head != null) { // When count is even subtract the nodes if (count % 2 == 0) if (difference == 0) { difference = head.data; } else { difference -= head.data; } // Count the nodes count++; // Move on the next node. head = head.next; } return difference; } // Function to push node at head static void push(Node head_ref, int new_data) { Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref;} // Driver code public static void Main(String[] args) { // Start with the empty list head = null; // Use push() function to con // the below list 8 . 23 . 11 . 29 . 12 push(head, 12); push(head, 29); push(head, 11); push(head, 23); push(head, 8); Console.WriteLine(" {0} ", subtractAlternateNode(head));}}// This code is contributed by PrinciRaj1992 |
Javascript
<script>// JavaScript program to print the difference // of Alternate Nodes // Structure of a node of the linked listclass Node { constructor() { this.data = 0; this.next = null; }}// Function to get the alternate// nodes of the linked listfunction subtractAlternateNode( head){ let count = 0; let difference = 0; while (head != null) { // When count is even subtract the nodes if (count % 2 == 0) if (difference == 0) { difference = head.data; } else { difference -= head.data; } // Count the nodes count++; // Move on the next node. head = head.next; } return difference;} // Function to push node at headfunction push(head_ref, new_data){ var new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref;}// Driver Code// Start with the empty listhead = null; // Use push() function to con// the below list 8 . 23 . 11 . 29 . 12push(head, 12);push(head, 29);push(head, 11);push(head, 23);push(head, 8); document.write(subtractAlternateNode(head)); </script> |
Output
-15
Time Complexity: O(N), where N is the number of nodes in the linked list
Auxiliary Space: O(1)
Recursive Approach :
- Initialize a static variable(say flag).
- If flag is odd, subtract the node from difference.
- increase head and flag by 1, and recurse for next nodes.
Below is the implementation of the above approach:
C++
// CPP code to print difference of alternate nodes// of a linked list using recursion#include <bits/stdc++.h>using namespace std;// A linked list nodestruct Node { int data; struct Node* next;};// Inserting node at the beginningvoid push(struct Node** head_ref, int new_data){ struct Node* new_node = (struct Node*) malloc(sizeof(struct Node)); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node;}// Function to find difference of alternate// nodes of linked list.// The boolean flag isOdd is used to find// if the current node is even or odd.void subtractAlternateNodes(struct Node* node, int& difference, bool isOdd = true){ if (node == NULL) return; if (isOdd == true) { if (difference == 0) { difference = node->data; } else { difference = difference - (node->data); } } subtractAlternateNodes(node->next, difference, !isOdd);}// Driver codeint main(){ // Start with the empty list struct Node* head = NULL; // Construct below list // 8 -> 23 -> 11 -> 29 -> 12 push(&head, 12); push(&head, 29); push(&head, 11); push(&head, 23); push(&head, 8); int difference = 0; subtractAlternateNodes(head, difference); cout << difference; return 0;} |
Java
// Java code to print difference of // alternate nodes of a linked list // using recursionclass GFG {// A linked list nodestatic class Node { int data; Node next;};static Node head; static int difference;// Inserting node at the beginningstatic Node push(Node head_ref, int new_data){ Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref; return head;}// Function to find difference of alternate// nodes of linked list.// The boolean flag isOdd is used to find// if the current node is even or odd.static void subtractAlternateNodes(Node node, boolean isOdd){ if (node == null) return; if (isOdd == true) { if (difference == 0) { difference = node.data; } else { difference = difference - (node.data); } } subtractAlternateNodes(node.next, !isOdd);}// Driver codepublic static void main(String[] args) { // Start with the empty list // Construct below list // 8 -> 23 -> 11 -> 29 -> 12 push(head, 12); push(head, 29); push(head, 11); push(head, 23); push(head, 8); difference = 0; subtractAlternateNodes(head, true); System.out.println(difference);}}// This code is contributed by PrinciRaj1992 |
Python
# Python code to print difference of alternate nodes# of a linked list using recursion# Link list node class Node: def __init__(self, data): self.data = data self.next = next # function to insert a node at the# beginning of the linked listdef push(head_ref, new_data): # allocate node new_node = Node(0) # put in the data new_node.data = new_data # link the old list to the new node new_node.next = (head_ref) # move the head to point to the new node (head_ref) = new_node return head_ref difference = 0;# Function to find difference of alternate# nodes of linked list.# The boolean flag isOdd is used to find# if the current node is even or odd.def subtractAlternateNodes(node, isOdd ): global difference if (node == None): return; if (isOdd == True): if (difference == 0) : difference = node.data; else : difference = difference - (node.data); subtractAlternateNodes(node.next, not isOdd);# Driver code# Start with the empty listhead = None;# Construct below list# 8 -> 23 -> 11 -> 29 -> 12head = push(head, 12);head = push(head, 29);head = push(head, 11);head = push(head, 23);head = push(head, 8);difference = 0;subtractAlternateNodes(head, True);print( difference);# This code is contributed by Arnab Kundu |
C#
// C# code to print difference of // alternate nodes of a linked list // using recursionusing System; class GFG {// A linked list nodepublic class Node { public int data; public Node next;};static Node head; static int difference;// Inserting node at the beginningstatic Node push(Node head_ref, int new_data){ Node new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref; return head;}// Function to find difference of alternate// nodes of linked list.// The boolean flag isOdd is used to find// if the current node is even or odd.static void subtractAlternateNodes(Node node, Boolean isOdd){ if (node == null) return; if (isOdd == true) { if (difference == 0) { difference = node.data; } else { difference = difference - (node.data); } } subtractAlternateNodes(node.next, !isOdd);}// Driver codepublic static void Main(String[] args) { // Start with the empty list // Construct below list // 8 -> 23 -> 11 -> 29 -> 12 push(head, 12); push(head, 29); push(head, 11); push(head, 23); push(head, 8); difference = 0; subtractAlternateNodes(head, true); Console.WriteLine(difference);}}// This code is contributed by Rajput-Ji |
Javascript
<script>// JavaScript code to print difference of // alternate nodes of a linked list // using recursion// A linked list nodeclass Node { constructor() { this.data = 0; this.next = null; }};var head= null;; var difference = 0;// Inserting node at the beginningfunction push(head_ref, new_data){ var new_node = new Node(); new_node.data = new_data; new_node.next = head_ref; head_ref = new_node; head = head_ref; return head;}// Function to find difference of alternate// nodes of linked list.// The boolean flag isOdd is used to find// if the current node is even or odd.function subtractAlternateNodes(node, isOdd){ if (node == null) return; if (isOdd == true) { if (difference == 0) { difference = node.data; } else { difference = difference - (node.data); } } subtractAlternateNodes(node.next, !isOdd);}// Driver code// Start with the empty list// Construct below list// 8 -> 23 -> 11 -> 29 -> 12push(head, 12);push(head, 29);push(head, 11);push(head, 23);push(head, 8);difference = 0;subtractAlternateNodes(head, true);document.write(difference);</script> |
Output
-15
Time Complexity: O(N) where N is number of nodes in the linked list
Auxiliary Space: O(N), for recursion call stack
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