传送门:Strategic Game 题意:用尽量少的顶点来覆盖所有的边. 分析:最小顶点覆盖裸题,最小顶点覆盖=最大匹配数(双向图)/2. #include <cstdio> #include <cstring> #include <string> #include <cmath> #include <iostream> #include <algorithm> #include <queue> #include <…

最小定点覆盖是指这样一种情况: 图G的顶点覆盖是一个顶点集合V,使得G中的每一条边都接触V中的至少一个顶点.我们称集合V覆盖了G的边.最小顶点覆盖是用最少的顶点来覆盖所有的边.顶点覆盖数是最小顶点覆盖的大小. 相应地,图G的边覆盖是一个边集合E,使得G中的每一个顶点都接触E中的至少一条边.如果只说覆盖,则通常是指顶点覆盖,而不是边覆盖. 在二分图中:最大匹配数=最小顶点覆盖数: Bob enjoys playing computer games, especially strategic gam…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 8503    Accepted Submission(s): 4093 Problem Description Bob enjoys playing computer games, especially strategic games, but somet…

题目链接:http://61.187.179.132/JudgeOnline/problem.php?id=3140 题意:最近在生物实验室工作的小T遇到了大麻烦. 由于实验室最近升级的缘故,他的分格实验皿是一个长方体,其尺寸为a*b*c.为了实验的方便,它被划分为a*b*c个单位立方体区域,每个单位立方体尺寸为1*1*1.用(i,j,k)标识一个单位立方体,1 ≤i≤a,1≤j≤b,1≤k≤c.这个实验皿已经很久没有人用了,现在,小T被导师要求将其中一些单位立方体区域进 行消毒操作(每个区域可…

http://poj.org/problem?id=3041 Asteroids Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12601   Accepted: 6849 Description Bessie wants to navigate her spaceship through a dangerous asteroid field in the shape of an N x N grid (1 <= N <…

Machine Schedule Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6701    Accepted Submission(s): 3358 Problem Description As we all know, machine scheduling is a very classical problem in comput…

分析:这里使用树形DP做. 1.最小顶点覆盖做法:最小顶点覆盖 == 最大匹配(双向图)/2. 2.树形DP: dp[i][0]表示i为根节点,而且该节点不放,所需的最少的点数. dp[i][1]表示i为根节点,而且该节点放,所须要的最少的点数. dp[i][0]=sum(dp[son[i][j]][1]) 该点不放.则它的儿子节点必须都放,仅仅有这样之间的边才干够被覆盖. dp[i][1]=sum(min(dp[son[i][j]][0],dp[son[i][j]][1])) 该点放的话,则它…

pid=1150">Machine Schedule Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 5424    Accepted Submission(s): 2691 Problem Description As we all know, machine scheduling is a very classical pro…

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 asteroids (1 <= K <= 10,000), which are conveniently located at the lattice points of the…

题目链接:[http://acm.hdu.edu.cn/showproblem.php?pid=1498] 题意:给出一个大小为n*n(0<n<100)的矩阵,矩阵中放入m种颜色(标号为1-m),然后对于每种颜色有k次操作,每次操作可以选择一行或者一列,然后把这一行或者这一列的这种颜色全部去掉,求每种颜色k次操作以后,不能去掉的颜色是哪几种颜色,从小到大输出. 最小顶点覆盖要求用最少的点(X或Y中都行),让每条边都至少和其中一个点关联.Knoig定理:二分图的最小顶点覆盖数等于二分图的最大匹配…