hdu Bone collector(01背包)_综合

Bone collector

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 51972 Accepted Submission(s): 21897

Problem Description

Many years ago , in Teddy’s hometown there was a man who was called “Bone Collector”. This man like to collect varies of bones , such as dog’s , cow’s , also he went to the grave …
The bone collector had a big bag with a volume of V ,and along his trip of collecting there are a lot of bones , obviously , different bone has different value and different volume, now given the each bone’s value along his trip , can you calculate out the maximum of the total value the bone collector can get ?

Input

The first line contain a integer T , the number of cases.
Followed by T cases , each case three lines , the first line contain two integer N , V, (N <= 1000 , V <= 1000 )representing the number of bones and the volume of his bag. And the second line contain N integers representing the value of each bone. The third line contain N integers representing the volume of each bone.

Output

One integer per line representing the maximum of the total value (this number will be less than 2 ³¹).

Sample Input

Sample Output

Author

Teddy

/*01背包问题，这种背包特点是：每种物品仅有一件，可以选择放或不放。
用子问题定义状态：即dp[i][v]表示前i件物品恰放入一个容量为v的背包可以获得的最大价值。
则其状态转移方程便是：
dp[i][v]=max{dp[i-1][v],dp[i-1][v-cost[i]]+value[i]}注意体积为零的情况，如：
1
5 0
2 4 1 5 1
0 0 1 0 0
结果为12*/
#include<stdio.h>
#include<string.h>
#define max(a,b) a>b?a:b
int dp[1000][1000];
int val[1000];
int wig[1000];
int main()
{int t;int m,n;int i,j;scanf("%d",&t);while(t--){scanf("%d%d",&n,&m);for(i=1;i<=n;i++)scanf("%d",&val[i]);for(i=1;i<=n;i++)scanf("%d",&wig[i]);memset(dp,0,sizeof(dp));//初始化操作for(i=1;i<=n;i++)for(j=0;j<=m;j++){if(j>=wig[i])//表示第i个物品将放入大小为j的背包中dp[i][j]=max(dp[i-1][j],dp[i-1][j-wig[i]]+val[i]);//第i个物品放入后，那么前i-1个物品可能会放入也可能因为剩余空间不够无法放入elsedp[i][j]=dp[i-1][j];//第i个物品无法放入}printf("%d\n",dp[n][m]);}return 0;
}
<pre name="code" class="cpp">/*该题的第二种解法就是对背包的优化解法，当然只能对空间就行优化，时间是不能优化的。先考虑上面讲的基本思路如何实现，肯定是有一个主循环i=1..N，每次算出来二维数组dp[i][0..V]的所有值。
那么，如果只用一个数组dp[0..V]，能不能保证第i次循环结束后dp[v]中表示的就是我们定义的状态dp[i][v]呢？dp[i][v]是由dp[i-1][v]和dp[i-1][v-c[i]]两个子问题递推而来，能否保证在推dp[i][v]时（也即在第i次主循环中推dp[v]时）能够得到dp[i-1][v]和dp[i-1][v-c[i]]的值呢？事实上，这要求在每次主循环中我们以v=V..0的顺序推dp[v]，这样才能保证推dp[v]时dp[v-c[i]]保存的是状态dp[i-1][v-c[i]]的值。伪代码如下：for i=1..Nfor v=V..0dp[v]=max{dp[v],dp[v-c[i]]+w[i]};注意：这种解法只能由V--0，不能反过来，如果反过来就会造成物品重复放置！*/
#include<stdio.h>
#include<string.h>
#define max(a,b) a>b?a:b
int dp[1000];
int val[1000];
int wig[1000];
int main()
{int t;int m,n;int i,j;scanf("%d",&t);while(t--){scanf("%d%d",&n,&m);for(i=1;i<=n;i++)scanf("%d",&val[i]);for(i=1;i<=n;i++)scanf("%d",&wig[i]);memset(dp,0,sizeof(dp));//初始化操作for(i=1;i<=n;i++)for(j=m;j>=0;j--){if(j>=wig[i])//表示第i个物品将放入大小为j的背包中dp[j]=max(dp[j],dp[j-wig[i]]+val[i]);//第i个物品放入后，那么前i-1个物品可能会放入也可能因为剩余空间不够无法放入elsedp[j]=dp[j];//第i个物品无法放入}printf("%d\n",dp[m]);}return 0;
}