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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c++ code:
class Solution {
public:
bool isPalindrome(string s) {
if(0 == s.size()) return true;
int i=0,j=s.size()-1;
while(i<=j){
while(!isA(s[i]) && i<j) i++;
while(!isA(s[j]) && i<j) j--;
if(tolower(s[i])!=tolower(s[j]))
return false;
i++;j--;
}
return true;
}
bool isA(char c){
if('a'<=c && c<='z' || 'A'<=c && c<='Z' || '0'<=c && c<='9')
return true;
else
return false;
}
};原文：http://blog.csdn.net/itismelzp/article/details/51588422