LeetCode | Valid Palindrome

Valid Palindrome

Total Accepted: 55178 Total Submissions: 251068My Submissions

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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Have you met this question in a real interview?

Yes

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思路：首先把给定字符串里的是数字或者字母的存起来到temp字符串，然后对temp进行判断，思路还是很清晰的。如果一个字符是，那么我就应该将它添加到这个temp中，但是实现遇到了一点麻烦，主要是字符没办法直接添加到temp中。解决方案是：

char tmp[1];

tmp[0]=s[i]; //是数字或者字母

string result(tmp,1);

temp+=result;

实现代码如下：

class Solution {
public:
    bool isPalindrome(string s) {
       string temp;
       for(int i=0;i<s.length();i++)
       {
           if(isalnum(s[i])){
            if(s[i]>='A'&&s[i]<='Z')
                s[i]=s[i]+32;
            char tmp[1];
            tmp[0] = s[i] ;
            string result(tmp,1);
            temp+=result;
           }
       }
      // cout<<temp<<endl;
       for(int i=0,j=temp.length()-1;i<j;i++,j--)
       {
           if(temp[i]!=temp[j])
            return false;
       }
       return true;
    }
};