1552: Friends Time Limit: 3 Sec Memory Limit: 256 MBSubmit: 723 Solved: 198[Submit][Status][Web Board] Description On an alien planet, every extraterrestrial is born with a number. If the sum of two numbers is a prime number, then two extraterrestr…
给一个数组,对于每两个数加起来为素数那么就是一个集合,求不超过k个集合的最多数是多少 解法:二分图匹配,先打素数筛,预处理边集,匹配完之后分两种情况k>匹配数,那么可以直接输出匹配数*2,否则可以选取匹配数*2+min(k-匹配数,剩余没有匹配的而且有边的点),这里是因为没有匹配的点有边,连着之前匹配过的点,我们可以复用,只要保证不超过k个集合就可以了, #include<bits/stdc++.h> #include<ext/rope> #define fi first #…
There is a class consisting of n students, in which each one has a number representing his/her personality. The teacher gives the students a new assignment and asks them to solve it in groups so that each group can contain two students at most. Stude…
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…
