UVA11729 - Commando War

G	Commando War Input: Standard Input Output: Standard Output

 

 

“Waiting for orders we held in the wood, word from the front never came

By evening the sound of the gunfire was miles away

Ah softly we moved through the shadows, slip away through the trees

Crossing their lines in the mists in the fields on our hands and our knees

And all that I ever, was able to see

The fire in the air, glowing red, silhouetting the smoke on the breeze”

 

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 N 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). B seconds are needed to brief the soldier while completing his job needs J 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.

 

Sample Input                                               Output for Sample Input

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

Case 1: 8 Case 2: 15

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Problem Setter: Mohammad Mahmudur Rahman, Special Thanks: Manzurur Rahman Khan

题目大意：指挥官需要分别派遣N个特种兵去完成相应的任务，第i特种兵在出发去完成任务之前需要指挥官的指导，需要耗费B[i]的时间，完成任务需要J[i]的时间，问怎么安排指导顺序使得特种兵们完成所有任务所需总时间最少。

题解：排序+贪心。

View Code

 1 #include<stdio.h>

 2 #define MAXSN 10000

 3 struct node

 4 {

 5     int b;

 6     int j;

 7 }s[MAXSN+5];

 8 void qsort(int l,int r)

 9 {

10     int i,j,mid;

11     struct node temp;

12     i=l; j=r; mid=s[(l+r)>>1].j;

13     while(i<=j)

14     {

15         while(s[i].j<mid) i++;

16         while(s[j].j>mid) j--;

17         if(i<=j)

18         {

19             temp=s[i];

20             s[i]=s[j];

21             s[j]=temp;

22             i++;

23             j--;

24         }

25     }

26     if(i<r) qsort(i,r);

27     if(j>l) qsort(l,j);

28 

29 }

30 int main(void)

31 {

32     long ans;

33     int i,m,n,t;

34     t=1;

35     while(scanf("%d",&n)!=EOF)

36     {

37         if(!n) break;

38         for(i=0;i<n;i++)

39         scanf("%d%d",&s[i].b,&s[i].j);

40         qsort(0,n-1);

41         m=0;

42         ans=0;

43         for(i=n-1;i>=0;i--)

44         {

45             m+=s[i].b;

46             if(ans<(m+s[i].j)) ans=m+s[i].j;

47         }

48         printf("Case %d: %ld\n",t++,ans);

49     }

50     return 0;

51 }