很裸,左点阵n,右点阵m 问最大匹配是否为n #include <cstdio> #include <cstring> #include <vector> using namespace std; vector <int> edge[103]; int pre[303]; bool vis[303]; int n, m; bool dfs(int u) { for(int i = 0; i < (int)edge[u].size(); i++) { i…

COURSES Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 16877   Accepted: 6627 Description Consider a group of N students and P courses. Each student visits zero, one or more than one courses. Your task is to determine whether it is poss…

COURSES Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 18993   Accepted: 7486 Description Consider a group of N students and P courses. Each student visits zero, one or more than one courses. Your task is to determine whether it is poss…

这道题实现起来还是比较简单的,但是理解起来可能有点困难. 我最开始想到的是贪心法,每次消灭当前小行星最多的一行或一列.然而WA了.Discuss区里已经有高人给出反例. 下面给出正确的解法 我们把行和列抽象成点,把小行星抽象成边,每出现一个小行星,就把其行列所对应的点连起来.这样就形成了一个无向图$G=\left(V, E\right)$.问题就转化为了求这个图G中的最小点覆盖,即求一个元素数量尽可能小的点集$V' \subset V$,$E$中的所有边均与其内的一点相连. 最小点覆盖问题是一个…

Chessboard Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 12800   Accepted: 4000 Description Alice and Bob often play games on chessboard. One day, Alice draws a board with size M * N. She wants Bob to use a lot of cards with size 1 * 2…

题意:每头奶牛都只愿意在她们喜欢的那些牛栏中产奶,告诉每头奶牛愿意产奶的牛棚编号,求出最多能分配到的牛栏的数量. 分析:直接二分图匹配: #include<stdio.h> #include<memory.h> #define MAX 202 bool flag,visit[MAX]; //记录V2中的某个点是否被搜索过 int match[MAX]; //记录与V2中的点匹配的点的编号 int cow, stall; //二分图中左边.右边集合中顶点的数目 int head[MA…

题意:给定一个图,然后有几个门,每个人要出去,但是每个门每个秒只能出去一个,然后问你最少时间才能全部出去. 析:初一看,应该是像搜索,但是怎么保证每个人出去的时候都不冲突呢,毕竟每个门每次只能出一个人,并不好处理,既然这样,我们可以把每个门和时间的做一个二元组,然后去对应每个人,这样的话,就是成了二分图的匹配,就能做了. 代码如下: #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio&g…

题意:在通讯录中有N个人,每个人能可能属于多个group,现要将这些人分组m组,设各组中的最大人数为max,求出该最小的最大值 下面用的是朴素的查找,核心代码find_path复杂度是VE的,不过据说可以用DINIC跑二分图可以得到sqrt(v)*E的 #include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <cmath> #incl…

                                                                 COURSES Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 21527   Accepted: 8460 Description Consider a group of N students and P courses. Each student visits zero, one or mo…

Problem DescriptionFrank N. Stein is a very conservative high-school teacher. He wants to take some of his students on an excursion, but he is afraid that some of them might become couples. While you can never exclude this possibility, he has made so…