description:

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

Example 1:Input: 121Output: trueExample 2:Input: -121Output: falseExplanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.Example 3:Input: 10Output: falseExplanation: Reads 01 from right to left. Therefore it is not a palindrome.

my answer:

class Solution {public:    bool isPalindrome(int x) {        if(x<0) return false;        string s;        while(x!=0){            int add = x%10;            s+='0'+add;            x = x/10;        }        int n = s.size();        for(int i = 0; i < n/2; i++){            if(s[i]!=s[n-1-i]) return false;        }        return true;    }};

大佬的answer：

class Solution {public:    bool isPalindrome(int x) {        if(x<0||(x%10==0&&x!=0))return false;        return reverse(x)==x;    }    int reverse(int x){        int res = 0;        while(x!=0){            if(res>INT_MAX/10)return -1;//这里很有意思，溢出好像都是判断INT_MAX/10的？            res = res*10 + x%10;            x /= 10;        }        return res;    }};

relative point get√：

emmm, string and integer 交换好像都需要'0' 作为跳板咩...？

hint :

res>INT_MAX/10)return -1

res = res*10 + x%10;

x /= 10;