UVa 624 CD （DP 01背包）

Posted on In ,

题意 你要把CD上的歌录到tape上 使得剩余磁带空间最小 很容易看出是01背包问题 输出路径也很容易 直接递归

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int s,n,val[30],d[1000005],pre[1000005];
void print(int i)
{
    if(pre[i])
    {
        print(pre[i]);
        printf("%d ",i-pre[i]);
    }
    else
    {
        printf("%d ",i);
        return;
    }
}
int main()
{
    while(scanf("%d %d",&s,&n)!=EOF)
    {
        memset(d,0,sizeof(d));
        memset(pre,0,sizeof(pre));
        for(int i=0; i<n; ++i)
        {
            scanf("%d",&val[i]);
            for(int j=s; j>=val[i]; --j)
                if(d[j-val[i]]+val[i]>d[j])
                {
                    d[j]=d[j-val[i]]+val[i];
                    pre[j]=j-val[i];
                }
        }
        print(d[s]);
        printf("sum:%d\n",d[s]);

    }
    return 0;
}

You have a long drive by car ahead. You have a tape recorder, but unfortunately your best music is on CDs. You need to have it on tapes so the problem to solve is: you have a tapeNminutes long. How to choose tracks from CD to get most out of tape space and have as short unused space as possible.

Assumptions:

Program should find the set of tracks which fills the tape best and print it in the same sequence as the tracks are stored on the CD

Any number of lines. Each one contains valueN, (after space) number of tracks and durations of the tracks. For example from first line in sample data:N=5, number of tracks=3, first track lasts for 1 minute, second one 3 minutes, next one 4 minutes

Set of tracks (and durations) which are the correct solutions and string ``sum:” and sum of duration times.

5 3 1 3 4 10 4 9 8 4 2 20 4 10 5 7 4 90 8 10 23 1 2 3 4 5 7 45 8 4 10 44 43 12 9 8 2

1 4 sum:5 8 2 sum:10 10 5 4 sum:19 10 23 1 2 3 4 5 7 sum:55 4 10 12 9 8 2 sum:45

Miguel A. Revilla
2000-01-10