104 lines
2.5 KiB
Java
104 lines
2.5 KiB
Java
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//给你一个字符串 s，找到 s 中最长的回文子串。
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//
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//
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//
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// 示例 1：
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//
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//
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//输入：s = "babad"
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//输出："bab"
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//解释："aba" 同样是符合题意的答案。
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//
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//
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// 示例 2：
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//
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//
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//输入：s = "cbbd"
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//输出："bb"
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//
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//
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// 示例 3：
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//
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//
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//输入：s = "a"
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//输出："a"
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//
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//
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// 示例 4：
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//
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//
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//输入：s = "ac"
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//输出："a"
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//
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//
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//
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//
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// 提示：
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//
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//
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// 1 <= s.length <= 1000
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// s 仅由数字和英文字母（大写和/或小写）组成
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//
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// Related Topics 字符串 动态规划
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// 👍 3593 👎 0
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package leetcode.editor.cn;
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import java.util.Collections;
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//5:最长回文子串
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public class LongestPalindromicSubstring {
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public static void main(String[] args) {
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//测试代码
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Solution solution = new LongestPalindromicSubstring().new Solution();
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//bab
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System.out.println(solution.longestPalindrome("babad"));
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//bb
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System.out.println(solution.longestPalindrome("cbbd"));
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//a
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System.out.println(solution.longestPalindrome("a"));
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//a
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System.out.println(solution.longestPalindrome("ac"));
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//ccc
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System.out.println(solution.longestPalindrome("ccc"));
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}
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//力扣代码
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//leetcode submit region begin(Prohibit modification and deletion)
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class Solution {
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public String longestPalindrome(String s) {
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int length = s.length();
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if (length < 2) {
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return s;
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}
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boolean[][] bl = new boolean[length][length];
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for (int i = 0; i < length; i++) {
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bl[i][i] = true;
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}
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int index = 0;
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int max = 1;
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for (int i = 2; i <= length; i++) {
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for (int start = 0; start < length && i + start - 1 < length; start++) {
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int end = i + start - 1;
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if (s.charAt(start) != s.charAt(end)) {
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bl[start][end] = false;
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} else {
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if (i <= 3) {
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bl[start][end] = true;
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} else {
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bl[start][end] = bl[start + 1][end - 1];
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}
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}
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if (bl[start][end] && i > max) {
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max = i;
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index = start;
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}
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}
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}
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return s.substring(index, index + max);
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}
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}
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//leetcode submit region end(Prohibit modification and deletion)
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}
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