[CodeVS 3269]混合背包

danihao123 posted @ 2016年8月14日 20:14 in 题解 with tags 动态规划 codevs 0-1背包 背包DP 完全背包 多重背包 , 615 阅读
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哎……现在才敢说真正会背包DP……

这个题可以分成三类问题分别处理,然后用一个一维数组一起递推。

0-1背包和完全背包都很简单。多重背包直接递推的话复杂度很高,可以考虑单调队列优化……然而窝太弱……不过还是用了

代码:

#include <cstdio>
#include <algorithm>
#include <queue>
#include <deque>
using namespace std;
const int maxn=201,maxv=200001;
struct DQueue{
    deque<int> D;
    queue<int> Q;
    void push(int x){
        Q.push(x);
        while(!D.empty() && x>D.back())
            D.pop_back();
        D.push_back(x);
    }
    int top(){
        return D.front();
    }
    void pop(){
        if(D.front()==Q.front())
            D.pop_front();
        Q.pop();
    }
    int size(){
        return Q.size();
    }
    void clear(){
        while(!Q.empty())
            Q.pop();
        D.clear();
    }
};
int d[maxv];
int v;
void pack(int V,int W,int c){
	register int i,j,m;
	if(c==1){
		for(i=v;i>=V;i--)
			d[i]=max(d[i],d[i-V]+W);
	}else{
		if(c==-1){
			for(i=V;i<=v;i++)
				d[i]=max(d[i],d[i-V]+W);
		}else{
			c=min(c,v/V);
			for(i=0;i<V;i++){
				m=(v-i)/V;
				DQueue Q;
				for(j=0;j<=m;j++){
					if(Q.size()==c+1)
						Q.pop();
					Q.push(d[j*V+i]-j*W);
					d[j*V+i]=Q.top()+j*W;
				}
			}
		}
	}
}
int main(){
	register int i;
	int n,x,y,z;
	scanf("%d%d",&n,&v);
	for(i=1;i<=n;i++){
		scanf("%d%d%d",&x,&y,&z);
		pack(x,y,z);
	}
	printf("%d\n",d[v]);
	return 0;
}
12thmodelpaper.in 说:
Jul 03, 2023 11:38:09 AM

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