Building roads Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 8153   Accepted: 2772 Description Farmer John's farm has N barns, and there are some cows that live in each barn. The cows like to drop around, so John wants to build some ro…

嘟嘟嘟 最近把21天漏的给不上. 今天重温了一下2-SAT,感觉很简单.就是把所有条件都转化成如果--必然能导出--.然后就这样连边建图,这样一个强连通分量中的所有点必然都是真或者假.从而根据这个点拆点后的两个点是否在一个强连通分量里判断是否有解. 这题人很容易想到拆点:\(i\)表示\(i\)连向\(s_1\),\(i + n\)表示\(i\)连向\(s_2\). 这道题关键在于距离这个限制.我们肯定能想到二分,但是接下来我就没想出来,因为2-SAT的图的边权是没有意义的.但实际上这个也是可以…

题目 Farmer John's farm has N barns, and there are some cows that live in each barn. The cows like to drop around, so John wants to build some roads to connect these barns. If he builds roads for every pair of different barns, then he must build N * (N…

题目连接 http://poj.org/problem?id=3625 Building Roads Description Farmer John had just acquired several new farms! He wants to connect the farms with roads so that he can travel from any farm to any other farm via a sequence of roads; roads already conn…

Building roads Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 6229   Accepted: 2093 Description Farmer John's farm has N barns, and there are some cows that live in each barn. The cows like to drop around, so John wants to build some ro…

计算距离时平方爆了int结果就WA了一次...... ----------------------------------------------------------------------------------------- #include<cstdio> #include<cstring> #include<algorithm> #include<iostream> #include<vector> #include<cmath…

HDU 1815, POJ 2749 Building roads pid=1815" target="_blank" style="">题目链接HDU 题目链接POJ 题意: 有n个牛棚, 还有两个中转站S1和S2, S1和S2用一条路连接起来. 为了使得随意牛棚两个都能够有道路联通,如今要让每一个牛棚都连接一条路到S1或者S2. 有a对牛棚互相有仇恨,所以不能让他们的路连接到同一个中转站. 还有b对牛棚互相喜欢,所以他们的路必须连到同一个中专站.…

Building roads Time Limit: 10000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 34 Accepted Submission(s): 13   Problem Description Farmer John's farm has N barns, and there are some cows that live in each barn.…

P2872 [USACO07DEC]道路建设Building Roads kruskal求最小生成树. #include<iostream> #include<cstdio> #include<cstring> #include<cmath> #include<queue> #include<algorithm> #define re register using namespace std; typedef double ld; t…

1626: [Usaco2007 Dec]Building Roads 修建道路 Time Limit: 5 Sec  Memory Limit: 64 MB Description Farmer John最近得到了一些新的农场,他想新修一些道路使得他的所有农场可以经过原有的或是新修的道路互达(也就是说,从任一个农场都可以经过一些首尾相连道路到达剩下的所有农场).有些农场之间原本就有道路相连. 所有N(1 <= N <= 1,000)个农场(用1..N顺次编号)在地图上都表示为坐标为(X_i,…