9. Palindrome Number | Leetcode solution

 9. Palindrome Number

Given an integer x, return true if x is palindrome integer.

An integer is a palindrome when it reads the same backward as forward.

• For example, 121 is a palindrome while 123 is not.

 

Example 1:

Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.

Example 2:

Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

 

Constraints:

• -231 <= x <= 231 - 1

solution:

class Solution {

public:

    bool ip(string s , int i , int j)

    {   

        if(i >j)

            return true;

        if(s[i]!= s[j])

            return false;

        return ip(s, i+1 , j-1);

    }

    bool isPalindrome(int x) {

        if(x < 0)

            return false;

        string s = to_string(x);

        int i = 0;

        int j = s.length()-1;

        return ip(s , i , j);

        

    }

};

references : https://leetcode.com/problems/palindrome-number/