传送门:hdu 5800 To My Girlfriend 题意:给定n个物品,其中i,j必选,l,m必不选,问组成体积为s的方法一共有多少种 思路:定义dp[i][j][s1][s2],表示前i种物品能够构成的体积为j,其中有s1种定为必选,s2种定为不必选;因为递推到第i层时,只与第i-1层有关,所以把第一维降到2来省内存.然后就是dp[i][j][s1][s2]=dp[i-1][j][s1][s2]+dp[i-1][j][s1][s2-1]+dp[i-1][j-a[i]][s1-1][s2…

To My Girlfriend Time Limit: 2000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1288    Accepted Submission(s): 492 Problem Description Dear Guo I never forget the moment I met with you.You carefully asked me:…

题意:求选中若干个数,满足和为S,且不能选中下表i, j 和选中k, l的情况总数量. 思路:DP[i][j][k][l] i:前i个和为j,选中k个和不选中l个的情况数量,那么我们的转换应该是在必选/必不选中扩展,还有就是可以都不用,和最多不超过2个选和不选.然后由于i.j之间可以互换位置,k.l之间也可以互换位置所以结果需要乘以4. #include<bits/stdc++.h> using namespace std; typedef long long ll; ; ; ; unsign…

题目 Source http://acm.hdu.edu.cn/showproblem.php?pid=5800 Description Dear Guo I never forget the moment I met with you.You carefully asked me: "I have a very difficult problem. Can you teach me?".I replied with a smile, "of course".&qu…

分析:首先定义状态dp[i][j][s1][s2]代表前i个物品中,选若干个物品,总价值为j 其中s1个物品时必选,s2物品必不选的方案数 那么转移的时候可以考虑,第i个物品是可选可可不选的 dp[i][j][s1][s2]+=dp[i-1][j][s1][s2]+dp[i-1][j-a[i]][s1][s2] 或者第i个物品必选,或者必不选 dp[i][j][s1][s2]+=dp[i-1][j-a[i]][s1-1][s2]+dp[i-1][j][s1][s2-1] 一点感想:这个题边界时d…

[题目链接]http://acm.hdu.edu.cn/showproblem.php?pid=5800 [题目大意] 给出一个容量上限s,f[i][j][k][l][m]表示k和l两个物品不能选,i和j两个物品必选,最终质量为m的方案数.求这些方案数的总和. [题解] 令dp[i][j][s1][s2]表示前i个物品填了j的体积,有s1个物品选为为必选,s2个物品选为必不选的方案数(0<=s1,s2<=2),则有转移方程dp[i][j][s1][s2]=dp[i-1][j][s1][s2]+…

2016暑假多校联合---To My Girlfriend Problem Description Dear Guo I never forget the moment I met with you.You carefully asked me: "I have a very difficult problem. Can you teach me?".I replied with a smile, "of course"."I have n items,…

Washing Clothes Time Limit: 1000MS   Memory Limit: 131072K Total Submissions: 9707   Accepted: 3114 Description Dearboy was so busy recently that now he has piles of clothes to wash. Luckily, he has a beautiful and hard-working girlfriend to help him…

Problem To My Girlfriend (HDU 5800) 题目大意 给定一个由n个元素组成的序列,和s (n<=1000,s<=1000) 求 :   f (i,j,k,l,m) 指必定选第i,j号元素,必定不选k,l号元素,选的元素总和为m的子集个数. 解题分析 一开始想了个n^3的DP,f[j][k]表示选j个数总和为k的方案数,然后一直想着怎么去优化,陷进死胡同,到比赛结束还没想出来. 看了题解后,感觉智商被藐视了. 题解的做法是f[i][j][s1][s2]表示前i个数总…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5800 To My Girlfriend Time Limit: 2000/2000 MS (Java/Others)Memory Limit: 65536/65536 K (Java/Others) 问题描述 Dear Guo I never forget the moment I met with you.You carefully asked me: "I have a very diffic…