题目：

题解：

class Solution {
public:bool isPalindrome(string s) {int n = s.size();int left = 0, right = n - 1;while (left < right) {while (left < right && !isalnum(s[left])) {++left;}while (left < right && !isalnum(s[right])) {--right;}if (left < right) {if (tolower(s[left]) != tolower(s[right])) {return false;}++left;--right;}}return true;}
};