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125.ValidPalindrome.cpp
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27 lines (24 loc) · 907 Bytes
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/*
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.
Tags: string, two points
*/
//Code:
bool isPalindrome(string s) {
for (int i = 0, j = s.size() - 1; i < j; ++i, --j)
{
//while (i < j && !isalpha(s[i])) //用isalpha会导致数字字符不被判断
while (i < j && !isalnum(s[i]))
++i;
while (i < j && !isalnum(s[j]))
--j;
if (tolower(s[i]) != tolower(s[j]))
return false;
}
return true;
}