leetcode[125]:Valid Palindrome

最新推荐文章于 2021-05-09 05:51:44 发布

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本文介绍了一个判断字符串是否为回文的算法实现，该算法只考虑字母数字字符，并忽略大小写。通过具体示例展示了如何逐个比较字符来确定字符串是否为回文。

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Valid Palindrome

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.

bool isPalindrome(char* s) {
    int i,j;
    if(!s) return true;
    j=strlen(s)-1;
    i=0;
    while(i<j)
    {

        if(s[i]>='A' && s[i]<='Z') s[i]+=32;
        if(s[j]>='A' && s[j]<='Z') s[j]+=32;
        if(s[i]<48 || s[i]>122 || (s[i]>57 && s[i]<97) ) {i++;continue;}
        if(s[j]<48 || s[j]>122 || (s[j]>57 && s[j]<97)) {j--;continue;}
        if(s[i]!=s[j]) break;
        i++,j--;
    } 
    if(i<j) return false;
    return true;
}