首页 > ACM题库 > UVA > Uva-11729-Commando War[贪心]
2014
02-24

Uva-11729-Commando War[贪心]

Commando War

There is a war and it doesn’t look very promising for your country. Now it’s time to act. You have a commando squad at your disposal and planning an ambush on an important enemy camp located nearby. You have soldiers in your squad. In your master-plan, every single soldier has a unique responsibility and you don’t want any of your soldier to know the plan for other soldiers so that everyone can focus on his task only. In order to enforce this, you brief every individual soldier about his tasks separately and just before sending him to the battlefield. You know that every single soldier needs a certain amount of time to execute his job. You also know very clearly how much time you need to brief every single soldier. Being anxious to finish the total operation as soon as possible, you need to find an order of briefing your soldiers that will minimize the time necessary for all the soldiers to complete their tasks. You may assume that, no soldier has a plan that depends on the tasks of his fellows. In other words, once a soldier  begins a task, he can finish it without the necessity of pausing in between.

Input

There will be multiple test cases in the input file. Every test case starts with an integer N (1<=N<=1000), denoting the number of soldiers. Each of the following N lines describe a soldier with two integers B (1<=B<=10000) J (1<=J<=10000)seconds are needed to brief the soldier while completing his job needs seconds. The end of input will be denoted by a case with N =0 . This case should not be processed.

Output

For each test case, print a line in the format, “Case X: Y”, where X is the case number & Y is the total number of seconds counted from the start of your first briefing till the completion of all jobs.

样例输入:

3
2 5
3 2
2 1
3
3 3
4 4
5 5
0

样例输出:

Case 1: 8
Case 2: 15

白皮书第二题。

直觉告诉我们,执行时间较长的任务应该先交待。按j排序即可。

第一点,任意交换两个任务对其他的任务执行时间不会有影响。

//============================================================================
// Name        : uva-28436.cpp
// Author      : coder
// Version     :
// Copyright   : www.acmerblog.com
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <algorithm>
#include <stdio.h>
using namespace std;
struct N{
	int b,j;
	int x;
};
N arr[1001];
bool cmp(const  N & n1,const N&  n2){
	return n1.j > n2.j;
}
int main() {
	//freopen("in.txt", "r", stdin);
	int n;
	int c = 0;
	while( cin >> n,n){
		c++;
		for(int i=0; i<n; i++){
			cin >> arr[i].b >> arr[i].j;
			arr[i].x = arr[i].j-arr[i].b;
		}
		sort(arr, arr+n, cmp);
		int mx = 0, time = 0;
		for(int i=0; i<n; i++){
			time += arr[i].b;
			if(arr[i].j + time > mx){
				mx = arr[i].j + time;
			}
		}
		cout << "Case " << c <<": " << mx << endl;
	}
	return 0;
}

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