[LeetCode]5. Longest Palindromic Substring（自学留存）

最新推荐文章于 2025-07-16 16:59:19 发布

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#C #LeetCode

本文介绍了一种高效算法来找出给定字符串中的最长回文子串。通过迭代检查每个字符为中心的回文情况，该算法能有效找到最长的回文子串。文章通过实例演示了如何使用该算法解决问题。

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

Example:

Input: "babad"

Output: "bab"

Note: "aba" is also a valid answer.

Example:

Input: "cbbd"

Output: "bb"

Personal tips: Manacher算法，保存回文开始位置和回文长度。

class Solution {
public:
	string longestPalindrome(string s) {
		int n = s.size(), len = 0, start = 0;
		for (int i = 0; i < n; i++) {
			int left = i, right = i;
			while (right < n && s[right + 1] == s[right]) right++;
			i = right;
			while (left > 0 && right < n - 1 && s[left - 1] == s[right + 1]) {
				left--;
				right++;
			}

			if (len < right - left + 1) {
				len = right - left + 1;
				start = left;
			}
		}
		return s.substr(start, len);
	}
};