hdu 4632区间 dp

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HDU 4632 区间DP 取模

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…

hdu 4632(区间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…

hdu 4632区间dp 回文字串计数问题

Palindrome subsequence Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 131072/65535 K (Java/Others)Total Submission(s): 3183 Accepted Submission(s): 1328 Problem Description In mathematics, a subsequence is a sequence that can be derived f…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4632 用点容斥原理转移状态, dp[i][j]=dp[i+1][j]+dp[i][j-1]-dp[i+1][j-1] 当 s[i] == s[j], 要加上 dp[i+1][j-1] + 1: 我就是想的太复杂,而这个题有卡时间,无限TLE,悲剧啊! #include <cstdio> #include <cmath> #include <algorithm> #inclu…

hdu 4283 区间dp

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

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≤…

HDU 4293---Groups(区间DP)

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…