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.
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bool isPalindrome(string s) { string::iterator iter1 = s.begin(); string::iterator iter2 = s.end() - 1; while (iter1 <= iter2) { if (!isalpha(*iter1) && !isdigit(*iter1)) { iter1++; continue; } if (!isalpha(*iter2) && !isdigit(*iter2)) { iter2--; continue; } char c1 = tolower(*iter1); char c2 = tolower(*iter2); if (c1 != c2) return false; iter1++; iter2--; } return true; }
原文：http://www.cnblogs.com/sdlwlxf/p/5096994.html