NC141 #判断回文#

双指针。别用递归，字符串太长了会爆栈。

class Solution {
public:
    bool judge(string str) {
        int len = str.size();
        int left = 0, right = len - 1;
        while(left <= right)
        {
            if(str[left] != str[right]) return false;
            left++, right--;
        }
        return true;
    }
};