Leetcode 125 Valid Palindrome

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example, "A man, a plan, a canal: Panama" is a palindrome. "race a car" is not a palindrome.

Note: Have you consider that the string might be empty? This is a good question to ask during an interview.

For the purpose of this problem, we define empty string as valid palindrome.

判断是否为回文串。

将字符串去其他符号，大写转小写

将逆置后的字符串与没有逆置的对比。

class Solution {
public:
    bool isPalindrome(string s) {
        string temp;
        for(int i=0;i<s.size();i++)
        {
            if((s[i]>='a' && s[i]<='z') || (s[i]>='0' && s[i]<='9')) temp+=s[i];
            if((s[i]>='A' && s[i]<='Z') ) temp+=s[i]-'A'+'a';
        }
        string temp2=temp;
        reverse(temp.begin(),temp.end());
        return temp==temp2;
    }
};