LeetCode-Valid Palindrome

最新推荐文章于 2025-08-20 13:22:19 发布

转载最新推荐文章于 2025-08-20 13:22:19 发布 · 45 阅读

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原文链接：http://www.cnblogs.com/superzrx/p/3330140.html

文章标签：

#c/c++

本文介绍了一个C++实现的方法，用于判断一个字符串是否为回文，只考虑字母数字字符并忽略大小写。通过双指针技术从两端向中间扫描，跳过非字母数字字符进行比较。

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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.

class Solution {
public:
    bool isA(char c){
        return c>='a'&&c<='z'||c>='A'&&c<='Z'||c>='0'&&c<='9';
    }
    char lower(char c){
        if(c>='A'&&c<='Z')return c-'A'+'a';
        return c;
    }
    bool isPalindrome(string s) {
        
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(s.length()<=1)return true;
        int start=0,end=s.length()-1;
        while(true){
            while(start<s.length()&&!isA(s[start])){
                start++;
            }
            
            while(end>=0&&!isA(s[end])){
                end--;
            }
            if(start>end)break;
            if(lower(s[start])!=lower(s[end]))return false;
            start++;
            end--;
        }
        return true;
    }
};

转载于:https://www.cnblogs.com/superzrx/p/3330140.html