题目描述
判断题目给出的字符串是不是回文，仅考虑字符串中的字母字符和数字字符，并且忽略大小写
例如："A man, a plan, a canal: Panama"是回文
"race a car"不是回文
注意：
你有没有考虑过字符串可能为空？这是面试时应该提出的一个好问题。
针对这个问题，我们定义空字符串是回文
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.
示例2
输出
class Solution {
public:
/**
*
* @param s string字符串
* @return bool布尔型
*/
bool isPalindrome(string s) {
int i,j;
for(i=0,j=s.length()-1;i<j;++i,--j){
while(i<j && !isalnum(s[i])) ++i;
while(i<j && !isalnum(s[j])) --j;
if (i<j && tolower(s[i])!=tolower(s[j])) return false;
}
return true;
}
};