题目链接:https://vjudge.net/problem/UVALive-2038 题意:我看了原题,lrj的书上题意写错了,应该是最少点覆盖,当然可以用最大匹配去做,由于是树形的: 可以树形DP: d[u][0] : u 结点 不放: d[u][1] : u 结点放: #include <bits/stdc++.h> using namespace std; + ; int n; vector<int> G[maxn]; ]; int p[maxn]; int dfs(in…

Machine Schedule Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=1150 Description As we all know, machine scheduling is a very classical problem in computer science and has been studied for a very long history.…

题意即求一个最小顶点覆盖. 对于没有孤立点的图G=(V,E),最大独立集+最小顶点覆盖= V.(往最大独立集加点) 问题可以变成求树上的最大独立集合. 每个结点的选择和其父节点选不选有关, dp(u,1)表示父节点选,这时u不可选, dp(u,0)表示父节点不选,这时u可选可不选. #include<bits/stdc++.h> using namespace std; ; ]; ], clk; ],to[maxn<<],ec; void add(int u,int v) { to…

Machine Schedule Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=1150 Description As we all know, machine scheduling is a very classical problem in computer science and has been studied for a very long history.…

Bob enjoys playing computer games, especially strategic games, but sometimes he cannot find the solution fast enough and then he is very sad. Now he has the following problem. He must defend a medieval city, the roads of which form a tree. He has to…

本文出自:http://blog.csdn.net/dr5459 题目地址: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=4038 题目意思: 给你一棵树 要你在树上的一些点上放置士兵,放的节点上面是一个 问你怎样放最少的能使所有的边被照顾到,一个士兵可以同时照顾和他所处节点相连的边 解题思路: 最少点覆盖问题 可以用树形DP解决 我们把…

传送门:Muddy Fields 题意:一个由r行c列方格组成的田地,里面有若干个方格充满泥泞,其余方格都是草.要用长度不限,宽度为1的长木板来覆盖这些泥方格,但不能覆盖草地.最少要用多少个长木板. 分析:行列模型最小点覆盖,给连续行和列重新标号,然后每个字符*代表一条边,题目转换成用最少点覆盖所有的边(*). #include <cstdio> #include <cstring> #include <string> #include <cmath> #i…

Asteroids Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 24789   Accepted: 13439 Description Bessie wants to navigate her spaceship through a dangerous asteroid field in the shape of an N x N grid (1 <= N <= 500). The grid contains K a…

传送门 考虑贪心,控制某一维为1,另两位最大是最优的,也就是一次选一个厚度为1的面 那么对于每个点,可以有3种面是可以选到它的 然后gg 考虑二维的状态,一个平面,有些点,一次选一行或一列最优 那么每一个点i,j可以被行i和列j选中,将i->j连接一条边,每一条边就代表一个点 选取最少的点覆盖所有边就是最少点覆盖=最大匹配 因为a*b*c<=5000所以最小的那一维一定<=17,可以枚举这一维哪些面被一次清除, #include <cstdio> #include <c…

Matrix Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 2319    Accepted Submission(s): 1030 Problem Description Give you a matrix(only contains 0 or 1),every time you can select a row or a colu…