[LeetCode] Valid Palindrome

class Solution {public:    bool isPalindrome(string s) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        vector<char> v;                for (int i = 0; i < s.size(); i++) {            char ch = s[i];                        if (ch >= '0' && ch <= '9') {                v.push_back(ch);            } else if (ch >= 'a' && ch <= 'z') {                v.push_back(ch);            } else if (ch >= 'A' && ch <= 'Z') {                v.push_back(ch - 'A' + 'a');            }        }                int n = v.size();                for (int i = 0; i < n / 2; i++) {            if (v[i] != v[n - 1 - i])                return false;        }                return true;    }};

Small Case: 4ms

Large Case: 60ms

Time: O(n)

Space: O(n)