Question

In c++, using stack structure, write a program that will take a sequence of characters (string) and determine whether it is a palindrome. Use the linked version of the stack.

Answer 1

#include <malloc.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

char* stack;

int top = -1;

// push function

void push(char ele)

{

    stack[++top] = ele;

}

// pop function

char pop()

{

    return stack[top--];

}

// Function that returns 1

// if str is a palindrome

int isPalindrome(char str[])

{

    int length = strlen(str);

    // Allocating the memory for the stack

    stack = (char*)malloc(length * sizeof(char));

    // Finding the mid

    int i, mid = length / 2;

    for (i = 0; i < mid; i++) {

        push(str[i]);

    }

    // Checking if the length of the string

    // is odd, if odd then neglect the

    // middle character

    if (length % 2 != 0) {

        i++;

    }

    // While not the end of the string

    while (str[i] != '\0') {

        char ele = pop();

        // If the characters differ then the

        // given string is not a palindrome

        if (ele != str[i])

            return 0;

        i++;

    }

    return 1;

}

// Driver code

int main()

{

    char str[] = "madam";

    if (isPalindrome(str)) {

        printf("Yes");

    }

    else {

        printf("No");

    }

    return 0;

}