【题解】【字符串】【Leetcode】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.

思路：

这题不能更简单了，考察的是徒手写bug的能力= =

代码：

bool isPalindrome(string s) { 
    int n = s.length();
    int i = 0;
    int j = n-1;
    while(i<j){//while(i>j){//蠢哭了
        while(!isalnum(s[i]) && i<n) i++;//没加i<n会超时，不看题用isalpha()
        while(!isalnum(s[j]) && j>=0) j--;
        if(i<j && tolower(s[i++]) !=  tolower(s[j--])) //if(s[i++] !=  s[j--] && i>j)//自加自减最坑了, 不看题没用tolower()
            return false;
    }
    return true;
}