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// Source : https://oj.leetcode.com/problems/valid-palindrome/

// Author : Hao Chen

// Date : 2014-06-26

/**********************************************************************************

* 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.

**********************************************************************************/

class Solution {

public:

bool isPalindrome(string s) {

s = removeNoise(s);

for(int i=0; i<s.size()/2; i++){

if (s[i]!= s[s.size()-i-1]){

return false;

}

return true;

}

string removeNoise(string& s){

string d;

for(int i=0; i<s.size(); i++){

if(::isalpha(s[i]) || ::isdigit(s[i])){

d.push_back(::tolower(s[i]));

}

return d;

}

};