混合背包

http://codevs.cn/problem/3269/

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,m,dp[200005],v[200005],w[200005],num[200005];
int main()
{
    scanf("%d%d",&n,&m);
    for(int i = 1;i <= n;i ++)
        scanf("%d%d%d",&w[i],&v[i],&num[i]);
    for(int i = 1;i <= n;i ++)
    {
        if(num[i] == -1)
            for(int j = w[i];j <= m;j ++)
                dp[j] = max(dp[j],dp[j - w[i]] + v[i]);
        else if(num[i] == 1)
            for(int j = m;j >= w[i];j --)
                dp[j] = max(dp[j],dp[j - w[i]] + v[i]);
        else
        {
            int ji = 1,l = num[i]; //二进制拆分；
            while(num[i] >> 1)//为了避免拆完后的总价值高于总价值，提前一步跳出
            {
                for(int j = m;j >= w[i] * ji;j --)
                    dp[j] = max(dp[j],dp[j - w[i] * ji] + v[i] * ji);
                l -= ji;//记录还剩下多少可用的物品；
                num[i] >>= 1;
                ji <<= 1;
            }
            for(int j = m;j >= w[i] * l;j --)
                    dp[j] = max(dp[j],dp[j - w[i] * l] + v[i] * l);
        }
    }
    printf("%d",dp[m]);
}