62 lines
1.5 KiB
Java
62 lines
1.5 KiB
Java
package com.leetcode.string;
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/**
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*
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最长回文子串:
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给定一个字符串 s，找到 s 中最长的回文子串。你可以假设 s 的最大长度为 1000。
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示例 1：
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输入: "babad"
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输出: "bab"
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注意: "aba" 也是一个有效答案。
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示例 2：
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输入: "cbbd"
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输出: "bb"
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来源：力扣（LeetCode）
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链接：https://leetcode-cn.com/problems/longest-palindromic-substring
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著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
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* @author zeek
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*
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*/
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public class LongestPalindrome {
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public String longestPalindrome(String s) {
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if (s == null || s.length() < 1) {
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return "";
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}
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int start = 0, end = 0;
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for (int i = 0; i < s.length(); i++) {
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int len1 = expandAroundCenter(s, i, i);
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int len2 = expandAroundCenter(s, i, i + 1);
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int len = Math.max(len1, len2);
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if (len > end - start) {
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start = i - (len - 1) / 2;
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end = i + len / 2;
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}
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}
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return s.substring(start, end + 1);
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}
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public int expandAroundCenter(String s, int left, int right) {
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while (left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
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--left;
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++right;
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}
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return right - left - 1;
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}
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public static void main(String[] args) {
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LongestPalindrome rome = new LongestPalindrome();
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String s = "cbbd";
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String res = rome.longestPalindrome(s);
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System.out.println(res);
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}
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}
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