题目 String painter 给出两个字符串s1,s2.对于每次操作可以将 s1 串中的任意一个子段变成另一个字符.问最少需要多少步操作能将s1串变为s2串. 解析 太妙了这个题,mark一下. 这个题先考虑怎么由空串转化s2, \(f[i][j]\)表示从空串到s2最少的次数, 则有\(f[i][j]=s[i+1][j]+1\), 若\([i+1,j]\)存在一个\(k\),使\(s2[i]==s2[k]\),则\(f[i][j]=min\{f[i+1][k]+f[k+1][j]\}\)…

题目链接:https://vjudge.net/problem/HDU-2476 String painter Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 5023    Accepted Submission(s): 2375 Problem Description There are two strings A and B wit…

题目链接:http://acm.split.hdu.edu.cn/showproblem.php?pid=2476 Problem Description There are two strings A and B with equal length. Both strings are made up of lower case letters. Now you have a powerful string painter. With the help of the painter, you c…

题意 String painter Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 6669    Accepted Submission(s): 3230 Problem Description There are two strings A and B with equal length. Both strings are made…

题意:要把a串变成b串,每操作一次,可以使a串的[l,r]区间变为相同的一个字符.问把a变成b最少操作几次. 这题写法明显是区间dp ,关键是处理的方法. dp[l][r]表示b串的l~r区段至少需要刷几次.这个值直接在b串中讨论,不用考虑a串. 之后用一个数组ans[i]来帮助求答案,ans[i]表示把a串的[0,i]区段刷成b对应区段所刷的次数. #include<iostream> #include<string.h> using namespace std; ][]; #d…

http://acm.hdu.edu.cn/showproblem.php?pid=2476 题目大意是给定一个起始串和一个目标串,然后每次可以将某一段区间染成一种字符,问从起始串到目标串最少需要染多少步? 读完题首先会想到的自然是用区间dp,但是列出来发现,没办法区间合并.因为一旦需要考虑对某一段成段染色的话,在区间合并的时候,就无法考虑转移过程中起始串的变化了. 既然这样,就不考虑成段染色造成的影响了,就当起始串和目标串处处不想等. 那么考虑区间[i, i+len], 自然遍历子区间[i, …

String painter Time Limit: 5000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2520    Accepted Submission(s): 1134 Problem Description There are two strings A and B with equal length. Both strings are made up…

// uva live 4394 String painter // // 问题是,在培训指导dp运动主题,乍一看,我以为只是一点点复杂 // A A磕磕磕,两个半小时后,.发现超过例子.然而,鉴于他们跪在数据 // 还要wa.才发现,自己的方法是有问题的,假设是将两个串同一时候考虑 // 的话.比方: dp[i][j] 表示从i到j,s串刷成目标b串所须要的最小的花费 // 然后依据区间的端点的字符特点,进行状态转移.然而可能是我太搓了. // 发现这种状态转移是不正确的,比方edc和cde.…

String painter Time Limit: 5000/2000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 2792 Accepted Submission(s): 1272 Problem Description There are two strings A and B with equal length. Both strings are made up of lo…

There are two strings A and B with equal length. Both strings are made up of lower case letters. Now you have a powerful string painter. With the help of the painter, you can change a segment of characters of a string to any other character you want.…