找中间的数,然后从两头取. #include<stdio.h> ; int pos[MAX]; int main() { int n,m,tmp; int i; int pol; long long ans,dis; while(scanf("%d %d",&n,&m)!=EOF) { ;i<=n;i++) scanf("%d",&pos[i]); pol=n/+; tmp=m; ans=; ;i<=pol;) { d…

题意:给定一位空间里n个点的坐标,每个坐标有一个罪犯,现在要建一个警局,并且这个警局只有一辆车,车一次最多载m个人,问应建在哪是的抓回所有罪犯的路程和最小. 思路: 很明显建在罪犯的点上一定可以找到最优解. 那么直接枚举建在哪一个点.. 那么抓罪犯肯定从两边抓最优.所以预处理两个数组即可.. code: #include <bits/stdc++.h> using namespace std; typedef long long ll; ], n, m; ll sl[], sr[]; void…

思路:删除尽量多的边使得所有点都能在限制距离之内到达一个警局,删除边会形成多棵子树,最多只能k棵.其实就是以每个警局为根结点,把整棵树划分为以警局为根结点的k棵树,说明要删除的边的数量就是k-1条,即删除的边的条数是一定的.剩下就是为每个节点找根结点,考虑从所有警局出发得到到每个点的最短距离,则当前节点u,一定是从u->v,如果d[v] <= lim则这条边一定会保留. AC代码 #include <cstdio> #include <cmath> #include &…

题意:给定 n 个数,有正数和-1, -1表示罪犯,正数表示招了几个警察,一个警察只能看一个罪犯,并且要按顺序,问你有多少罪犯逃脱. 析:很简单么,从开始扫到最后,把是正数就加上,是-1判断剩余警察大于0,如果是就让警察数减1,如果不是答案加1. 代码如下: #include <bits/stdc++.h> using namespace std; typedef long long LL; const int maxn = 1e5 + 5; const int INF = 0x3f3f3f3…

今天是水题集啊.... A. Police Recruits time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output The police department of your city has just started its journey. Initially, they don’t have any manpower. So,…

Checkposts Time Limit: 2000ms Memory Limit: 262144KB This problem will be judged on CodeForces. Original ID: 427C64-bit integer IO format: %I64d      Java class name: (Any)     Your city has n junctions. There are m one-way roads between the junction…

20170710: hdu1074,hdu1087,hdu1114,hdu1159,hdu1160,hdu1171,hdu1176,hdu1010,hdu1203 20170711: hdu1231,hdu1257,hdu1260,hdu1284,hdu1421,hdu1789,hdu1978,hdu2059,hdu2084 20170712: hdu2159,hdu2191,hdu2544,hdu2571,hdu2602,hdu2709,hdu1015,hdu1016 20170713: co…

题目链接: http://codeforces.com/problemset/problem/208/C C. Police Station time limit per test:2 secondsmemory limit per test:256 megabytes 问题描述 The Berland road network consists of n cities and of m bidirectional roads. The cities are numbered from 1 to…

地址:http://codeforces.com/contest/796/problem/D 题目: D. Police Stations time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Inzane finally found Zane with a lot of money to spare, so they togeth…

题目链接:http://codeforces.com/contest/208/problem/C 思路:题目要求的是经过1~N的最短路上的某个点的路径数 /  最短路的条数的最大值.一开始我是用spfa得到从1开始的最短路和从N开始的最短路,然后分别从N开始记忆化搜索,得到从1到达最短路径上的u的路径条数,记作dp1[u], 然后再从1开始搜,得到最短路径上从N到达某个点u的路径条数,记作dp2[u],于是经过某个点u的最短路径数目为dp1[u] * dp2[u],然后只需枚举u求最大值即可.…

[题目链接]:http://codeforces.com/contest/796/problem/D [题意] 在一棵树上,保证每个点在距离d之内都有一个警察局; 让你删掉最多的边,使得剩下的森林仍然满足上述约束; [题解] 从每个警察局开始进行bfs; 这样每个路线第一次到达的点肯定是最短路; 所以bfs的时候遇到没访问过的点,就记录它被访问,即它被这个状态一开始的警察局所管辖(控制); 则可以想象每个警察局都同时往外扩张; 则每个警察局管的范围就确定是那些了; 则那些点肯定是到那个管辖它的警…

题目的意思就是找出未能及时处理的犯罪数, #include <iostream> using namespace std; int main(){ int n; cin >> n; , crimes = ;; ; i < n; ++ i){ cin >> a; ) recruit+=a; else recruit?recruit-- : crimes++; } cout<<crimes<<endl; }…

大意: 给定树, 有k个黑点, 初始满足条件:所有点到最近黑点距离不超过d, 求最多删除多少条边后, 使得原图仍满足条件. 所有黑点开始bfs, 贪心删边. #include <iostream> #include <algorithm> #include <math.h> #include <cstdio> #include <set> #include <map> #include <string> #include…

传送门 题意 n个点有n-1条边相连,其中有k个特殊点,要求: 删去尽可能多的边使得剩余的点距特殊点的距离不超过d 输出删去的边数和index 分析 比赛的时候想不清楚,看了别人的题解 一道将1个联通块转化为k个树的题目,考虑上界,应该是k-1条边,这k-1条边是原图中连接树与树的边,那么我们操作如下: 1.将特殊点i染色为i,放入队列 2.做一次bfs,对每个点相邻的点染色并判断 3.遍历边,如果边的两点不同色,则输出边的index trick 代码 #include <cstdio> #i…

B. Bear and Finding Criminals 链接:http://codeforces.com/contest/680/problem/B There are n cities in Bearland, numbered 1 through n. Cities are arranged in one long row. The distance between cities i and j is equal to |i - j|. Limak is a police officer…

Police Recruits Time Limit: 1000MS   Memory Limit: 262144KB   64bit IO Format: %I64d & %I64u Submit Status Description The police department of your city has just started its journey. Initially, they don’t have any manpower. So, they started hiring n…

C. Robbers' watch time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Robbers, who attacked the Gerda's cab, are very successful in covering from the kingdom police. To make the goal of catchi…

B. Bear and Finding Criminals time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output There are n cities in Bearland, numbered 1 through n. Cities are arranged in one long row. The distance betwee…

B. Rebranding Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/591/problem/B Description The name of one small but proud corporation consists of n lowercase English letters. The Corporation has decided to try rebranding — an…

D. Tablecity Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/575/problem/D Description There was a big bank robbery in Tablecity. In order to catch the thief, the President called none other than Albert – Tablecity’s Chief o…

决定在 codeforces 练题啦,决定每个比赛刷前四道...太难就算了 796A Buying A House 题意:给出x轴上的n 个点,每个点有个权值,问离m 点最近的权值小于等于k 的点离m的距离.单位是10. 思路:大水题.用l.r分别向左向右找即可. 代码: #include<stdio.h> int main(){ int n, m, k; ]; while(~scanf("%d%d%d", &n, &m, &k)){ ; i<…

就像title说的,是昨天(2017/9/17)周赛的两道水题…… 题目链接:http://codeforces.com/problemset/problem/14/A time limit per test: 1 second memory limit per test: 64 megabytes A boy Bob likes to draw. Not long ago he bought a rectangular graph (checked) sheet with n rows and…

A. Robbers' watch time limit per test: 2 seconds memory limit per test: 256 megabytes input: standard input output: standard output Robbers, who attacked the Gerda's cab, are very successful in covering from the kingdom police. To make the goal of ca…

A. Robbers' watch 题目连接: http://www.codeforces.com/contest/685/problem/A Description Robbers, who attacked the Gerda's cab, are very successful in covering from the kingdom police. To make the goal of catching them even harder, they use their own watc…

B. Bear and Finding Criminals 题目连接: http://www.codeforces.com/contest/680/problem/B Description There are n cities in Bearland, numbered 1 through n. Cities are arranged in one long row. The distance between cities i and j is equal to |i - j|. Limak…

题目链接: http://codeforces.com/problemset/problem/507/E E. Breaking Good time limit per test2 secondsmemory limit per test256 megabytes 问题描述 Breaking Good is a new video game which a lot of gamers want to have. There is a certain level in the game that…

Bank Hacking 阅读题,读完之后手算一下可以发现每一个bank被hack所需要的strength无非分为三种情况. 1. $a_i$,当且仅当i为第一个选择的点. 2. $a_i+1$,当且仅当i是第一个选择的点的neighborhood. 3. $a_i+2$,其他所有点. 这样,分类讨论即可. http://codeforces.com/contest/796/submission/26318700 Police Stations 猜想题,可以注意到因为给定的图是树,那么每删除一条…

上一次我们拿学校的URP做了个小小的demo.... 其实我们还可以把每个学生的证件照爬下来做成一个证件照校花校草评比 另外也可以写一个物理实验自动选课... 但是出于多种原因,,还是绕开这些敏感话题.. 今天,我们来扒一下cf的题面! PS:本代码不是我原创 1. 必要的分析 1.1 页面的获取 一般情况CF的每一个 contest 是这样的: 对应的URL是:http://codeforces.com/contest/xxx 还有一个Complete problemset页面,它是这样的:…

http://codeforces.com/contest/738/problem/D Galya is playing one-dimensional Sea Battle on a 1 × n grid. In this game a ships are placed on the grid. Each of the ships consists of bconsecutive cells. No cell can be part of two ships, however, the shi…

http://codeforces.com/contest/738/problem/C Vasya is currently at a car rental service, and he wants to reach cinema. The film he has bought a ticket for starts in t minutes. There is a straight road of length s from the service to the cinema. Let's…