LeetCode -- Valid Palindrome

题目描述：


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.

判断回文。需要跳过特殊字符以及同一个字母大小写视为相等的情况。

实现代码：

public class Solution {
    public bool IsPalindrome(string s) 
    {
        var i = 0;
    	var j = s.Length - 1;
    	while(i < j){
    		while(Skip(s[i]) && i < j){
			i++;
    		}
    		while(Skip(s[j]) && i < j){
    			j--;
    		}
    		
    		var delta = s[i] - s[j];
    		if(delta != 0 && delta != 32 && delta != -32){
    			return false;
    		}
    		
        		
    		i++;
    		j--;
    	}
    	
    	return true;
    }


    public bool Skip(char c)
    {
    	var a = (int)'a';
    	var A = (int)'A';
    	var z = (int)'z';
    	var Z = (int)'Z';
    	var v = (int)c;
    	
    	var zero = (int)'0';
    	var nine = (int)'9';
    	
    	if(v >= a && v <= z || v >= A && v <= Z || v >= zero && v <= nine){
    		return false;	
    	}
    	
    	return true;
    }


}