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.
解题思路:
类似快排的写法,两头逼近。去掉不满足条件的字符,然后做个比較就可以.
解题代码:
class Solution { public: bool isPalindrome(string s) { bool res = true; int i = 0, j = s.size() - 1; while ( res && i < j) { while (i < j && !(isdigit(s[i]) || isalpha(s[i]))) ++i; while (i < j && !(isdigit(s[j]) || isalpha(s[j]))) --j; if (i < j) { res = s[i] == s[j] || abs(s[i] - s[j]) == 32; ++i, --j; } } return res; } };
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