先将多重背包转换成01背包,然后贪心排序求最大值。
AC代码:
#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<string.h>
#define inf 1ll<<30
using namespace std;
int dp[41111],val[411],num[411],cost;
struct block{
int cost,val;
}b[2111];
bool cmp(block a,block b){
if(a.cost == b.cost) return a.val > b.val; //贪心排序,因为这个大于号WA了一发
return a.cost < b.cost;
}
int main(){
memset(dp,0,sizeof(dp));
int v = 0,n,p=1;
cin>>n;
for(int i=1;i<=n;++i){
cin>>val[i]>>cost>>num[i];
v = max(v,cost);
for(int j=1;j<=num[i];j<<=1){
b[p].cost = cost;
b[p].val = j*val[i];
num[i] -= j;
p++;
}
if(num[i]){
b[p].cost = cost;
b[p].val = num[i]*val[i];
p++;num[i]=0;
}
}
sort(b+1,b+p,cmp);
int mmax = 0;
for(int i=1;i<p;++i){
for(int j=b[i].cost;j>=b[i].val;--j){ //背包容量从cost开始才有效
dp[j] = max(dp[j],dp[j-b[i].val]+b[i].val);
mmax = max(mmax,dp[j]);
}
}
cout<<mmax<<endl;
return 0;
}