Codevs3269 混合背包 经典背包dp

01背包：倒着for。
完全背包：正着for。
多重背包：拆开做01背包，或者条件满足直接完全背包。

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cstdlib>
using namespace std;

#define MAXN (200+20)
#define MAXV (200000+20)
int n, V;
int dp[MAXV];

struct pack{
int c, v, num;
}l[MAXN];

void zeroonepack(int cost, int value)
{
for(int i = V; i >= cost; -- i)
dp[i] = max(dp[i], dp[i-cost]+value);
}

void compack(int cost, int value)
{
for(int i = cost; i <= V; ++ i)
dp[i] = max(dp[i], dp[i-cost]+value);
}

void multpack(int cost, int value, int num)
{
if(num*cost >= V)
compack(cost, value);
else{
int k = 1;
while(k < num)
{
zeroonepack(k*cost, k*value);
num -= k;
k <<= 1;
}
zeroonepack(num*cost, num*value);
}
}

int main()
{
cin >> n >> V;
for(int i = 1; i <= n; ++ i) scanf("%d%d%d", &l[i].c, &l[i].v, &l[i].num);

for(int i = 1; i <= n; ++ i)
{
if(l[i].num == 1)
zeroonepack(l[i].c, l[i].v);
else if(l[i].num == -1)
compack(l[i].c, l[i].v);
else multpack(l[i].c, l[i].v, l[i].num);
}

cout << dp[V];
return 0;
}