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C++ Program For Comparing Two Strings Represented As Linked Lists

  • Last Updated : 29 Dec, 2021

Given two strings, represented as linked lists (every character is a node in a linked list). Write a function compare() that works similar to strcmp(), i.e., it returns 0 if both strings are the same, 1 if the first linked list is lexicographically greater, and -1 if the second string is lexicographically greater.
Examples:

Input: list1 = g->e->e->k->s->a
       list2 = g->e->e->k->s->b
Output: -1

Input: list1 = g->e->e->k->s->a
       list2 = g->e->e->k->s
Output: 1

Input: list1 = g->e->e->k->s
       list2 = g->e->e->k->s
Output: 0

C++




// C++ program to compare two strings 
// represented as linked lists
#include<bits/stdc++.h>
using namespace std;
   
// Linked list Node 
// structure
struct Node
{
    char c;
    struct Node *next;
};
   
// Function to create newNode 
// in a linkedlist
Node* newNode(char c)
{
    Node *temp = new Node;
    temp->c = c;
    temp->next = NULL;
    return temp;
};
  
int compare(Node *list1, 
            Node *list2) 
{    
    // Traverse both lists. Stop when 
    // either end of a linked list is 
    // reached or current characters 
    // don't match
    while (list1 && list2 && 
           list1->c == list2->c) 
    {         
        list1 = list1->next;
        list2 = list2->next;
    }
      
    //  If both lists are not empty, 
    // compare mismatching characters
    if (list1 && list2) 
        return ((list1->c > 
                 list2->c)? 1: -1);
  
    // If either of the two lists has 
    // reached end
    if (list1 && !list2) return 1;
    if (list2 && !list1) return -1;
      
    // If none of the above conditions 
    // is true, both lists have reached 
    // end 
    return 0;
}
  
// Driver code
int main()
{
    Node *list1 = newNode('g');
    list1->next = newNode('e');
    list1->next->next = newNode('e');
    list1->next->next->next = 
           newNode('k');
    list1->next->next->next->next = 
           newNode('s');
    list1->next->next->next->next->next = 
           newNode('b');
  
    Node *list2 = newNode('g');
    list2->next = newNode('e');
    list2->next->next = newNode('e');
    list2->next->next->next = 
           newNode('k');
    list2->next->next->next->next =  
           newNode('s');
    list2->next->next->next->next->next = 
           newNode('a');
  
    cout << compare(list1, list2); 
    return 0;
}

Output: 

1

Please refer complete article on Compare two strings represented as linked lists for more details!


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