LeetCode: Valid Palindrome

基本一次过吧，题目没说数字要算进去啊。。

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