5. Longest Palindromic Substring

最长回文子串算法

最新推荐文章于 2025-07-16 16:59:19 发布

原创最新推荐文章于 2025-07-16 16:59:19 发布 · 190 阅读

0 ·

CC 4.0 BY-SA版权

算法同时被 2 个专栏收录

82 篇文章

订阅专栏

编程挑战

81 篇文章

订阅专栏

本文介绍了一种寻找字符串中最长回文子串的方法。通过定义一个辅助函数判断字符串是否为回文，并遍历字符串的所有可能子串来找出最长的回文子串。此算法适用于字符串长度不超过1000的情况。

5. Longest Palindromic Substring

Description Hints Submissions Discuss Solution

Pick One

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

class Solution {
     public boolean isPalindrome(String text) {
        int lastIndex = text.length() - 1;
        int firstIndex = 0;
        while (firstIndex <= lastIndex) {
            if (text.charAt(firstIndex) != text.charAt(lastIndex)) {
                return false;
            }
            ++firstIndex;
            --lastIndex;
        }
        return true;
    }

    public String longestPalindrome(String s) {
        if (s == null || s.isEmpty()) {
            return "";
        }
        int max = 1;
        String maxString = s.substring(0,1);
        for (int i = 0; i < s.length(); i++) {
            for (int j = i + 1; j < s.length(); j++) {
                String sub = s.substring(i, j + 1);
                int length = sub.length();
                boolean isp = isPalindrome(sub);
                if (isp) {
                    if (max < length) {
                        max = length;
                        maxString = sub;

                    }

                }
            }
        }

        return maxString;

    }

}