QSC and Master Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)Total Submission(s): 859    Accepted Submission(s): 325 Problem Description Every school has some legends, Northeastern University is the same. Enter…

题意:给你n对pair 里面有两个值,分别是key 和 val .你可以取相邻的两个pair 获得其中的val,前提是两个pair 的key 的 gcd 不为 1.当然你把相邻的两个取走了之后原本不相邻的两个就变得相邻了.比如:你将下标为 2,3 取走之后,下标1,4就变得相邻了,求你可以获得的最大val. 题解:典型的合并问题,应该能想到用区间dp,但这里得考虑清楚,状态怎么转移.我们定义dp[i][j]为i~j能够获取的最大值.那么怎么更新状态呢,我们用一个前缀和去维护val,如果 dp[i…

You Are the One Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 3348    Accepted Submission(s): 1524 Problem Description The TV shows such as You Are the One has been very popular. In order to m…

HDU 2829 区间DP & 前缀和优化 & 四边形不等式优化 n个节点n-1条线性边,炸掉M条边也就是分为m+1个区间 问你各个区间的总策略值最少的炸法 就题目本身而言,中规中矩的区间DP问题 d p[i][j]表示前i个节点,分为j个区间的最优策略值 cost[i][j]为从i到j节点的策略值 所以dp[i][j] = min(dp[k-1][j-1] + cost[k][i] 但是复杂度太高了 可以优化的地方有: cost数组值得求取: 考虑到cost(i,j)=ΣAxAy (i≤…

题目链接 http://acm.split.hdu.edu.cn/showproblem.php?pid=4293 Problem Description After the regional contest, all the ACMers are walking alone a very long avenue to the dining hall in groups. Groups can vary in size for kinds of reasons, which means, sev…

HDU - 2476 思路:分解问题,先考虑从一个空串染色成 B串的最小花费 ,区间DP可以解决这个问题 具体的就是,当 str [ l ] = = str [ r ]时 dp [ L ] [ R ] = min (dp [ L + 1] [ R ],dp [ L ] [ R-1 ] ) 其他情况可以选择任意一个断点 tmp = min ( tmp , dfs ( l  ,k ) + dfs ( k+1 , r ) ); 接下来就是第二步 现在A串不是空串 ,但然把它当做空串去染是没有问题的,…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=4632 注意到任意一个回文子序列收尾两个字符一定是相同的,于是可以区间dp,用dp[i][j]表示原字符串中[i,j]位置中出现的回文子序列的个数,有递推关系: dp[i][j]=dp[i+1][j]+dp[i][j-1]-dp[i+1][j-1] 如果i和j位置出现的字符相同,那么dp[i][j]可以由dp[i+1][j-1]中的子序列加上这两个字符构成回文子序列,也就是 dp[i][j]+=dp…

E - Multi-bit Trie Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u Description IP lookup is one of the key functions of routers for packets forwarding and classifying. Generally, IP lookup can be simplified as a Longest P…

题意: 给出两个串s1和s2,一次只能将一个区间刷一次,问最少几次能让s1=s2 例如zzzzzfzzzzz,长度为11,我们就将下标看做0~10 先将0~10刷一次,变成aaaaaaaaaaa 1~9刷一次,abbbbbbbbba 2~8:abcccccccba 3~7:abcdddddcba 4~6:abcdeeedcab 5:abcdefedcab 这样就6次,变成了s2串了 其 实如果a串是空串的话,我们可以写出这样的区间dp方程:设dp[i][j]表示从i到j至少要变多少次,则有dp[…

Palindrome subsequence Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/65535 K (Java/Others)Total Submission(s): 2858    Accepted Submission(s): 1168 Problem Description In mathematics, a subsequence is a sequence that can be derived f…