Gopher II Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 6345   Accepted: 2599 Description The gopher family, having averted the canine threat, must face a new predator. The are n gophers and m gopher holes, each at distinct (x, y) coor…

题目链接:http://poj.org/problem?id=2536 题意:已知有n仅仅老鼠的坐标,m个洞的坐标,老鼠的移动速度为V,S秒以后有一仅仅老鹰要吃老鼠,问有多少个老鼠被吃. 非常明晰,二分匹配,老鼠为X集合,洞为Y集合 思路:计算当前老鼠 Xi 到达洞 Yi 的时间(dis/v),假设小于S的话,则Xi与Yi联通, 被吃的老鼠数 = n - 最大匹配数 #include <iostream> #include <cstdio> #include <cstdlib…

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=1882 http://poj.org/problem?id=2536 题目大意: 有n之地鼠和m个地洞,他们需要在s秒内以v秒的速度跑进洞中,否则会被鹰抓走.给定每个地鼠和洞的坐标,每个洞最多容纳一只地鼠,问最小有危险的地鼠个数. 思路: 跑回学校了~来A几题. 几个月前看的题不会做T T,现在好简单... 本题可以转化为二分图匹配.如果地鼠到洞的时间小于s,那么久建一条边…

二分图的最大匹配 地鼠内部和地鼠洞内部都是没有边相连的,那么就可以看成一个二分图.地鼠如果可以跑到那个地鼠洞,就连一条边,然后跑二分图的最大匹配,最后地鼠的数量减去最大匹配数就是答案. #include<cstdio> #include<cstring> #include<cmath> #include<algorithm> using namespace std; ; int nx,ny; int g[MAXN][MAXN]; int cx[MAXN],c…

题意: N只地鼠M个洞,每只地鼠.每个洞都有一个坐标. 每只地鼠速度一样,对于每只地鼠而言,如果它跑到某一个洞的所花的时间小于等于S,它才不会被老鹰吃掉. 规定每个洞最多只能藏一只地鼠. 问最少有多少只地鼠会命丧鹰口. 思路: 直接建图.二分图最大匹配. 代码: char st[105]; char Range[25][5]; int n; int num[10]; int cx[25],cy[205]; bool bmask[205]; vector<int> graph[25]; int…

题目链接:http://poj.org/problem?id=3057 题目大概意思是有一块区域组成的房间,房间的边缘有门和墙壁,'X'代表墙壁,'D'代表门,房间内部的' . '代表空区域,每个空区域站一个人,人可以向上下左右走,每走一步花费一秒钟,现在房间起火了,所有人向四周的门逃生,但是每秒钟一扇门只能通过一个人,每个人移动到门时,就算逃脱,问在选取使得所有人最优的逃生方案时,最后一个逃生的人花费多长时间?如果有人无法逃生,输出impossible. 题目建图思路比较难想.考虑到任意 t…

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…

Selecting Courses Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 8316   Accepted: 3687 Description It is well known that it is not easy to select courses in the college, for there is usually conflict among the time of the courses. Li Mi…

Description The gopher family, having averted the canine threat, must face a new predator. The are n gophers and m gopher holes, each at distinct (x, y) coordinates. A hawk arrives and if a gopher does not reach a hole in s seconds it is vulnerable t…

[题目链接] http://poj.org/problem?id=2536 [算法] 匈牙利算法解二分图最大匹配 [代码] #include <algorithm> #include <bitset> #include <cctype> #include <cerrno> #include <clocale> #include <cmath> #include <complex> #include <cstdio&g…