百度之星C题

最大费用最大流

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

#define CLR(arr,v) memset(arr,v,sizeof(arr))
const int INF = 1<<29 ;

template<int MaxV,int MaxE>
class MinCostMaxFlow{
public:
	void Clear(){
		pos = 0;
		CLR(h,-1); CLR(Flow,0);
	}
	void add(int u,int v,int f,int c){
		num[pos] = v;
		cap[pos] = f;
		cost[pos] = c;
		next[pos] = h[u];
		h[u] = pos++;

		num[pos] = u;
		cap[pos] = 0;
		cost[pos] = -c;
		next[pos] = h[v];
		h[v] = pos++;
	}
	int GetMinCostMaxFlow(int start,int end){
		int cur,maxflow = 0,mincost = 0,minflow;
		while(SPFA(start,end)){
			cur = end;
			minflow = INF;
			while(cur != start){
				if(minflow > cap[ pre_e[cur] ] - Flow[ pre_e[cur] ])
					minflow = cap[ pre_e[cur] ] - Flow[ pre_e[cur] ];
				cur = pre_v[cur];
			}
			cur = end;
			maxflow += minflow;
			while(cur != start){
				Flow[ pre_e[cur] ] += minflow;
				Flow[ pre_e[cur]^1] -= minflow;
				mincost += minflow * cost[ pre_e[cur] ];
				cur = pre_v[cur];
			}
		}
		return mincost;
	}
private:
	int h[MaxV],dis[MaxV],num[MaxE],cap[MaxE],cost[MaxE],Flow[MaxE],next[MaxE],pre_e[MaxV],pre_v[MaxV],Q[MaxV],InQ[MaxV],pos;
	bool SPFA(int s,int t){
		CLR(dis,0);
		CLR(InQ,false);
		dis[s] = 1;
		int head = 0,total = 0,cur;
		Q[total++] = s;
		while(head != total){
			cur = Q[head++];
			if(head >= MaxV) head = 0;
			for(int i = h[cur];i != -1;i = next[i]){
				if(cap[i] > Flow[i] && dis[cur] + cost[i] > dis[ num[i] ]){
					dis[ num[i] ] = dis[cur] + cost[i];
					pre_v[ num[i] ] = cur;
					pre_e[ num[i] ] = i;
					if(!InQ[ num[i] ])
					{
						if(total >= MaxV) total = 0;
						InQ[ num[i] ] = true;
						Q[total++] = num[i];
					}
				}
			}
			InQ[cur] = false;
		}
		return dis[t] > 1;
	}
};

MinCostMaxFlow<2005,10000> g;

struct Friend{
	int x,y;
};
Friend f[1005];

struct Gift{
	int a,b,c;
};
Gift gift[5];

int main()
{
	int n;
	while(scanf("%d",&n) != EOF)
	{
		g.Clear();
		for(int i = 0;i < n;++i)
			scanf("%d%d",&f[i].x,&f[i].y);
		for(int i = 0;i < 2;++i)
		{
			scanf("%d%d%d",&gift[i].c,&gift[i].a,&gift[i].b);
			g.add(0,i+1,gift[i].c,0);
		}
		int val;
		for(int i = 0;i < 2;++i)
		{
			for(int j = 0;j < n;++j)
			{
				val = gift[i].a*f[j].x+gift[i].b*f[j].y;
				g.add(i+1,j+3,1,val);
			}
		}

		for(int i = 0;i < n;++i)
			g.add(i+3,n+3,1,0);
		printf("%d\n",g.GetMinCostMaxFlow(0,n+3));
	}
	return 0;
}