HDU 2546（01背包）

http://acm.hdu.edu.cn/showproblem.php?pid=2546

 

http://blog.csdn.net/xujinsmile/article/details/7969412

 

首先拿出5元买最贵的东西，那接下来就是背包容量m-5，物品数量n-1 的01背包问题了。

做背包问题一定要明确边界条件再入手，不然很费时间

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <stack>
using namespace std;

#define MEM(a,b) memset(a,b,sizeof(a))
#define pf printf
#define sf scanf
#define debug printf("!\n")
#define INF 8000
#define MAX(a,b) a>b?a:b
#define blank pf("\n")
#define LL long long
#define ep 1e-6

int dp[INF];

int ci[INF];//容量
int wi[INF];//价值
int n,V,i,j,v,t,sum;


void zeroOnePack(int cost,int weight)
{
          for(v = V-5;v>=cost;v--)
          {
                    dp[v] =MAX(dp[v],dp[v-cost]+weight);
          }
}

void completePack(int cost,int weight)
{
          for(v = cost;v<=V;v++)
          {
                    dp[v] =MAX(dp[v],dp[v-cost]+weight);
                    pf("tt%d %d %d\n",i,v,dp[v]);
          }

}

int main()
{

          int t;
          while(sf("%d",&n) && n)
          {

                    MEM(dp,0);
                    MEM(ci,0);
                    MEM(wi,0);

                    for(i = 1;i<=n;i++)
                    {
                              sf("%d",&wi[i]);
                    }

                    sort(wi+1,wi+n+1);

                    sf("%d",&V);

                    int m = wi[n];

                    if(V<5)
                    {
                              pf("%d\n",V);
                              continue;
                    }
                    else
                    {
                              n--;
                              for(i = 1;i<=n;i++)
                              {
                                        zeroOnePack(wi[i],wi[i]);
                              }

                              pf("%d\n",V-m-dp[V-5]);


                    }
          }
    return 0;
}