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.
这题是看答案写出来的，解题思路就是头尾匹配再前后数组下标向中间移位1，continue在这的作用有点费解，没有的话会报错，待研究。。。
1 class Solution { 2 public: 3 bool isValid(char c) { 4 return (c >= ‘a‘ && c <= ‘z‘) || (c >= ‘A‘ && c <= ‘Z‘) || (c >= ‘0‘ && c <= ‘9‘); 5 } 6 bool isPalindrome(string s) { 7 int start = 0, end = s.size() - 1; 8 while (start < end) { 9 if (!isValid(s[start])) { start ++; continue; } 10 if (!isValid(s[end])) { end --; continue; } 11 if (s[start] != s[end] && abs(s[start] - s[end]) != 32) return false; 12 start ++; 13 end --; 14 } 15 return true; 16 } 17 };
原文：http://www.cnblogs.com/sofeii/p/4058968.html