LeetCode(4) || Longest Palindromic Substring 与 Manacher 线性算法 题记 本文是LeetCode题库的第五题,没想到做这些题的速度会这么慢,工作之余全部耗在这上面了,只怪自己基础差.本文主要介绍使用Manacher线性算法来求解字符串的最长回文子字符串. 题目 Given a string S, find the longest palindromic substring in S. You may assume that the maxim…
Leetcode 5. Longest Palindromic Substring(最长回文子串, Manacher算法) Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: "bab" Note: "aba&q…
写在前面:忍不住吐槽几句今天上海的天气,次奥,鞋子里都能养鱼了...裤子也全湿了,衣服也全湿了,关键是这天气还打空调,只能瑟瑟发抖祈祷不要感冒了.... 前后切了一百零几道leetcode的题(solution同步在github),主要是拣难度系数定为easy的水题做...好吧,这是第一道算法题.不知哪位大神说的,所有的语言都会过时,只有数据结构和算法才是永恒. 今天要重点讲的是优雅的Manacher算法,先来看这道题Longest Palindromic Substring,题目很简单,给你一…
题目来源:https://leetcode.com/problems/longest-palindromic-substring/ Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 动态规划,类似于l…
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 解题思路一: 暴力枚举 共N^2量级个子串(从下标零开始),每次检查需一个for循环,等于是3重for循环,时间复杂度O(n^3) 解题思路二: 动态…
Question:Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.(给定一个字符串S,在S中找到最长的回文子字符串,假定最长的回文字符串长度是1000,并且在这个字符串中存在唯一的一个最长回文子字符串…
# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com'https://oj.leetcode.com/problems/longest-palindromic-substring/ Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000,and there e…
DP.KMP什么的都太高大上了.自己想了个朴素的遍历方法. [题目] Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. [思路](应该算是O(n)吧) 从中间向两端搜索.分别找到以每一个字母为中心的最…
Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Example 2: Input: "cbbd"…
题目描述 Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 即给定一个字符串,求它的最长回文子串的长度(或者最长回文子串). 解法一 对于一个问题,一定可以找到一个傻的可爱的暴力解法,本题的暴力解法即…
题目: Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 翻译: 找出字符串s中最长的回文子串,字符串s的最长是1000,假设存在唯一的最长回文子串 法一:直接暴力破解 O(N3)的时间复杂度,运行超…
问题描述: Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 解题思路: 遍历方法,时间复杂度为O(n).首先从字符串的开头位置一直往后遍历,在每次遍历的过程中由该位置向两边扩散,直到找到最长的子回文…
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 动态规划解法 O(n2) 超时 string longestPalindrome(string s) { if(s.empty()) return s…
题目: Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 解题:参考网上大神做法,解题如下: class Solution: def get_palindromic(self, s, k, l): s…
Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Example 2: Input: "cbbd"…
Longest Palindromic Substring 回文这种简单的问题,在C里面印象很深啊.希望能一次过. 写的时候才想到有两种情况: 454(奇数位) 4554(偶数位) 第1次提交 class Solution: def longestPalindrome(self, s): """ :type s: str :rtype: str """ print(s) maxPadStr='' # traverse each char l=le…
题目 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"…
Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. 求字符串中的最大回文子串(从左往右和从右往左读一样的子串). Example: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Exam…
lc 5 Longest Palindromic Substring 5 Longest Palindromic Substring 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: "ab…
很经典的一道题,最长回文子串,有多种方法. 首先介绍的一种方法是从中间向两边展开.注意区分aba和abba型的回文串:如果当前最长的子串已经当于两边中最长的子串了,则无需再去判断. //从中间向两边展开 string expandAroundCenter(string s, int c1, int c2) { int l = c1, r = c2; int n = s.length(); && r <= n - && s[l] == s[r]) { l--; r++;…
问题:https://leetcode.com/problems/longest-palindromic-substring/ 给定一个字符串 S,求出 S 的最长回文子串 思路: 1. 回文:一个字符串从前和从后读一致.S = "ABBA"  从前读:ABBA,从后读:ABBA 2. 最简单的做法:列出所有的子串,并判断是否是回文,从中找出最长的. 表格列出了所有的子串,第 i 行是以 S 的第 i 个字符开始的子串.S = "ABBA"  1  A  AB  A…
https://leetcode.com/problems/longest-palindromic-substring/ manacher算法相关:http://blog.csdn.net/ywhorizen/article/details/6629268 class Solution { public: string longestPalindrome(string s) { char ch[2001];int p[2001]; ch[2*s.size()] = 0; for(int i =…
public String longestPalindrome(String s) { String rs = ""; int res = 0; for(int i = 0; i< s.length(); i++){ int left = i, right = i; while(left >= 0 && s.charAt(i) == s.charAt(left)) left --; while(right < s.length() &&…
一.题目链接:https://leetcode.com/problems/longest-palindromic-substring/ 二.题目大意: 给定一个字符串,找出它最长的回文子串.例如,字符串“caabb”,它的最长回文子串为“aabb”. 三.题解: 找最长回文子串应该说是比较经典的题目,这个题目我目前有三种思路: 方法1:暴力解决,找出所有的子串,并判断子串是不是回文,然后记录最长的回文子串.代码如下: class Solution { public: string longest…
public String longestPalindrome(String s) { int start = 0, end = 0; for (int i = 0; i < s.length(); i++) { int len1 = expandAroundCenter(s, i, i); int len2 = expandAroundCenter(s, i, i + 1); int len = Math.max(len1, len2); if (len > end - start) { s…
原题链接 找到并返回最长回路子串 思路: 解法一: 最简单的双重遍历,判断s[i]到s[j]是不是回串. Runtime: 610 ms, faster than 6.39% of Java 慢的不行 class Solution { public String longestPalindrome(String s) { int len=s.length(); for (int i = 0; i < len; i++) { int subNum = i + 1; int subLen = len…
题目: 给定一个字符串S,返回S中最长的回文子串.S最长为1000,且最长回文子串是唯一. 解法: ①遍历,对于每个字符,计算以它为中心的回文子串长度(长度为奇数),同时计算以它和右边相邻字符为中心的回文子串长度(长度为偶数).时间为O(N2). ②另外,有一个很奇妙的算法,称为Manacher算法,参考 http://www.cnblogs.com/daoluanxiaozi/p/longest-palindromic-substring.html ,时间为O(N). 代码: ①直接扩展: c…
应用一下manacher算法就可以O(n)求出结果了.可以参考hdu3068 substr(start,length)函数是这样用的: substr 方法 返回一个从指定位置开始,并具有指定长度的子字符串. 参数 start 必选.所需的子字符串的起始位置.字符串中第一个字符的索引为 0. length 可选项.返回的子字符串中包含的字符数. 备注 如果 length 为 0 或负数,将返回一个空字符串.如果没有指定该参数,则子字符串将延续到字符串的结尾. class Solution { pu…
LeetCode: 5. Longest Palindromic Substring class Solution { public: //动态规划算法 string longestPalindrome(string s) { int n = s.length(); int longestBegin = 0; int maxLen = 1; bool table[1000][1000] = {false}; for (int i = 0; i < n; i++) { table[i][i] =…
Given a string s, find the longest palindromic subsequence's length in s. You may assume that the maximum length of s is 1000. Example 1:Input: "bbbab" Output: 4 One possible longest palindromic subsequence is "bbbb". Example 2:Input:…