LINK 题意:给出n个商品,除第一个商品外,所有商品可以选择使用优惠券,但要求其前驱商品已被购买,问消费k以下能买几个不同的商品 思路:题意很明显就是树形DP.对于一个商品有三种选择,买且使用优惠券,买不使用优惠券,不买.当然如果直接暴力进行转移是$O(n^3)$的,但我们可以统计每个结点其子节点的个数sz,sz~0地来遍历,这样就可以将某节点与其父节点进行转移,从而避免了多余无效的转移,优化到$O(n^2)$.dp[k][i][j]代表 k是否不使用优惠券,以i为父节点 购买j个商品的最小花…
Karen and Supermarket 感觉就是很普通的树形dp. dp[ i ][ 0 ][ u ]表示在 i 这棵子树中选择 u 个且 i 不用优惠券的最小花费. dp[ i ][ 1 ][ u ]表示在 i 这棵子树中选择 u 个且 i 用优惠券的最小花费. 注意这个转移总的合起来是O(n ^ 2)的. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk…
题目传送门 Karen and Supermarket On the way home, Karen decided to stop by the supermarket to buy some groceries. She needs to buy a lot of goods, but since she is a student her budget is still quite limited. In fact, she can only spend up to b dollars. T…
C. Karen and Supermarket On the way home, Karen decided to stop by the supermarket to buy some groceries. She needs to buy a lot of goods, but since she is a student her budget is still quite limited. In fact, she can only spend up to b dollars.…
E. Karen and Supermarket time limit per test 2 seconds memory limit per test 512 megabytes input standard input output standard output On the way home, Karen decided to stop by the supermarket to buy some groceries. She needs to buy a lot of goods, b…
Network Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 4478 Accepted: 1292 Description Yixght is a manager of the company called SzqNetwork(SN). Now she's very worried because she has just received a bad news which denotes that DxtNet…
Find Metal Mineral Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65768/65768 K (Java/Others)Total Submission(s): 3397 Accepted Submission(s): 1588 Problem Description Humans have discovered a kind of new metal mineral on Mars which are d…
