Cashier Employment Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 7651   Accepted: 2886 Description A supermarket in Tehran is open 24 hours a day every day and needs a number of cashiers to fit its need. The supermarket manager has hir…

http://poj.org/problem?id=1275 题目大意: 一商店二十四小时营业,但每个时间段需求的雇员数不同(已知,设为R[i]),现有n个人申请这份工作,其可以从固定时间t连续工作八个小时,问在满足需求的情况下最小需要多少个雇员. 思路: 挺难的..看了别人的思路搞半天.. 设num[ i ]为i时刻能够开始工作的人数,x[ i ]为实际雇佣的人数,那么x[ I ]<=num[ I ]. 设r[ i ]为i时刻至少需要工作的人数,于是有如下关系: x[ I-7 ]+x[ I-6…

http://poj.org/problem?id=1275 题意 : 一家24小时营业的超市,要雇出纳员,需要求出超市每天不同时段需要的出纳员数,午夜只需一小批,下午需要多些,希望雇最少的人,给出每小时需要的出纳员的最少数量,R(0),R(1),...,R(23).R(0)表示从午夜到凌晨1:00所需要出纳员的最少数目:R(1)表示凌晨1:00到2:00之间需要的:以此类推.这些数据每一天都是相同的.有N人申请这工作,申请者 i ,从一个特定的时刻开始连续工作恰好8小时.定义ti(0<=ti<…

A supermarket in Tehran is open 24 hours a day every day and needs a number of cashiers to fit its need. The supermarket manager has hired you to help him, solve his problem. The problem is that the supermarket needs different number of cashiers at d…

http://poj.org/problem?id=1275 #include <cstdio> #include <cstring> #include <algorithm> #define maxn 2000 using namespace std; <<; ],t[maxn],s[maxn],dis[maxn]; int n,e; int sum; struct node { int u,v,w; }p[maxn]; void add(int u,in…

Description Once, in one kingdom, there was a queen and that queen was expecting a baby. The queen prayed: ``If my child was a son and if only he was a sound king.'' After nine months her child was born, and indeed, she gave birth to a nice son. Unfo…

· 对于差分约束,题目要求求什么便设什么,令$Sum[i]$表示由$0 ~ i$的雇佣人数. · 要充分利用题目所给条件,令$Have[i]$表示i时刻申报的人数,$Need[i]$表示i时刻需要的人数「结合 “人数” 关键词」. 此时容易列出两个基本不等式:   Sum[i] - Sum[i - 1] >= 0;   Sum[i] - Sum[i - 1] <= Have[i]; 此时发现还有$Need[]$和范围为8个单位长度的区间没有使用,可得:   Sum[i] - Sum[i - 8…

Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 24099   Accepted: 9159 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a program that: reads the number of intervals, their end po…

Language:Default Candies Time Limit: 1500MS   Memory Limit: 131072K Total Submissions: 43021   Accepted: 12075 Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse…

经典的差分约束+二分答案. 本题的难点在于如何建图. 设x[i] 表示第i个小时可以开始工作的有多少个人. num[i] 表示第i个小时最少需雇佣多少人. s[i] 表示1...i小时实际开始工作的有多少人 因为最后要求的是s[24]的最小值,所以我们以s为中心建图. 因为我们求得是最小值,所以都转化成>=号的形式 我们逐步分析题目的已知条件: 第i小时实际开始工作的人数应小于等于可以开始的人数,即 $ s[i]-s[i-1]<=x[i] $ 变成 $ s[i-1]-s[i] >=-x[…

Like everyone else, cows like to stand close to their friends when queuing for feed. FJ has N (2 <= N <= 1,000) cows numbered 1..N standing along a straight line waiting for feed. The cows are standing in the same order as they are numbered, and sin…

题目传送门 题意:有两种关系,n牛按照序号排列,A1到B1的距离不超过C1, A2到B2的距离不小于C2,问1到n的距离最大是多少.如果无限的话是-2, 如果无解是-1 分析:第一种可以写这样的方程:d[v] - d[u] <= w1, u到v连一条权值为w1的边,第二种这样:d[v] - d[u] >= w2 => d[u] - d[v] <= -w2,v到u连一条-w2的边.当然根据题目还有i+1 到 i连权值0的边.最短路就是为了d[v] <= d[u] + w[u][…

Description The galaxy war between the Empire Draco and the Commonwealth of Zibu broke out 3 years ago. Draco established a line of defense called Grot. Grot is a straight line with N defense stations. Because of the cooperation of the stations, Zibu…

Intervals Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 30971 Accepted: 11990 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a program that: reads the number of intervals, their end point…

[POJ 1275] Cashier Employment(差分约束系统的建立和求解) Cashier Employment Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 7569   Accepted: 2856 Description A supermarket in Tehran is open 24 hours a day every day and needs a number of cashiers to f…

POJ 3159 Candies (图论,差分约束系统,最短路) Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse's class a large bag of candies and had flymouse distribute them. All the kids…

[HDU 1529]Cashier Employment(差分约束系统) 题面 有一个超市,在24小时对员工都有一定需求量,表示为\(r_i\),意思为在i这个时间至少要有i个员工,现在有n个员工来应聘,每一个员工开始工作的时间为\(t_i(i \in [0,23])\),并持续8小时,问最少需要多少员工才能达到每一个时刻的需求.前一天16点后的人统计入下一天 分析 预备知识:(如果你了解过差分约束,可以直接跳过) 首先讲一下差分约束系统的基本定义:如果一个系统由n个变量和m个约束条件组成,形成…

Cashier Employment Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 7997   Accepted: 3054 Description A supermarket in Tehran is open 24 hours a day every day and needs a number of cashiers to fit its need. The supermarket manager has hir…

题目地址:id=1275">POJ 1275 题意: 给出一个超市24小时各须要R[i]个雇员工作,有N个雇员能够雇佣.他们開始工作时间分别为A[i],求须要的最少的雇员人数. 思路:这个题的查约束太多了!简直是差评!只是也不是否能定这是道好题. 设dis[i]为0-i小时内工作的人数(dis[24]即为所求).r[i]为第(i-1)-i小时时须要在工作的人数,t[i]能够在第i-1小时開始工作.能够建立起下面约束不等式: 0 <= dis[i]-dis[i-1] <= t[i…

[题目链接] 点击打开链接 [算法] 设Ti为第i小时有多少个出纳员开始工作,Vi表示第i小时有多少个来应聘的出纳员 那么,有 : 1. 0 <= Ti <= Vi 2. Ti + Ti-1 + Ti-2 + Ti-3 + Ti-4 + Ti-5 + Ti-6 + Ti-7 >= Ri 令Si = T1 + T2 + T3 + ... Ti 则 : 1. Si >= Si-1 2. Si - Si-1 <= Vi 3. Si >= Si-8 + Ri( 8 <=…

Cashier Employment Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 1214    Accepted Submission(s): 537 Problem Description A supermarket in Tehran is open 24 hours a day every day and needs a nu…

[POJ1275]Cashier Employment 题意: 超市经历已经提供一天里每一小时需要出纳员的最少数量————R(0),R(1),...,R(23).R(0)表示从午夜到凌晨1:00所需要出纳员的最少数目:R(1)表示凌晨1:00到2:00之间需要的:等等.每一天,这些数据都是相同的. 有N人申请这项工作,每个申请者i在每天24小时当中,从一个特定的时刻开始连续工作恰好8小时.定义ti(0<=ti<=23)为上面提到的开始时刻,也就是说,如果第i个申请者被录用,他(或她)将从ti时…

id=1716">[POJ 1716]Integer Intervals(差分约束系统) Integer Intervals Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 13425   Accepted: 5703 Description An integer interval [a,b], a < b, is a set of all consecutive integers beginning with…

id=2983">[POJ 2983]Is the Information Reliable? (差分约束系统) Is the Information Reliable? Time Limit: 3000MS   Memory Limit: 131072K Total Submissions: 12244   Accepted: 3861 Description The galaxy war between the Empire Draco and the Commonwealth of…

[POJ 1201] Intervals(差分约束系统) 11 1716的升级版 把原本固定的边权改为不固定. Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 23817   Accepted: 9023 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a p…

Layout 题目链接: Rhttp://acm.hust.edu.cn/vjudge/contest/122685#problem/S Description Like everyone else, cows like to stand close to their friends when queuing for feed. FJ has N (2 <= N <= 1,000) cows numbered 1..N standing along a straight line waitin…

介绍下差分约束系统:就是多个2未知数不等式形如(a-b<=k)的形式 问你有没有解,或者求两个未知数的最大差或者最小差 转化为最短路(或最长路) 1:求最小差的时候,不等式转化为b-a>=k的标准形式建图,求最长路 2:求最大差的时候,不等式转化为b-a<=k的标准形式建图,求最短路 然后具体的写的好的博客以供大家参考 1 http://www.cnblogs.com/void/archive/2011/08/26/2153928.html 2 http://blog.csdn.net/…

Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 20779   Accepted: 7863 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn.  Write a program that:  reads the number of intervals, their end…

题目链接:https://cn.vjudge.net/contest/276233#problem/A 差分约束系统,假设当前有三个不等式 x- y <=t1 y-z<=t2 x-z<=t3 我们可以将第一个式子和第二个式子结合起来,就变成了x-z<= t1+t2 ,然后x-z的最大差值就是min(t1+t2,t3)(因为要使得最终结果都满足两个不等式) 然后求最小的过程(求差最大),就可以通过最短路的算法实现. 题目大意:给你n代表有n头牛,然后ml和md,接下来ml行,每行有三…

差分约束系统 我们先来认识一下差分约束系统鸭! 差分约束系统是一种特殊的\(n\)元一次不等式组,它包含了\(n\)个变量\(x_1-x_n\)以及\(m\)个不等式(约束条件).其中每一个不等式形如\(x_i-x_j\leq c_k\),\(c_k\)是常数,\(i,j \leq n,k \leq m\). 通常来说,题目会给出这一些限制条件的模型或变式,我们需要在满足这个不等式组的前提下求解一些指定的数值. 注意到不等式\(x_i-x_j\leq c_k\)我们可以将其转换为\(x_i\le…