POJ 3422 kaka's matrix trvals（费用流）

标签：acm

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <cmath>
#define LL long long 
using namespace std;
const int maxn = 10000 + 10;
const int INF = 0x3f3f3f3f;
struct Edge
{
	int from, to, cap, flow, cost;
	Edge(int u, int v, int c, int f, int w) : from(u), to(v), cap(c), flow(f), cost(w) { }
};
int n;
vector<Edge>edges;
vector<int>G[maxn];
int inq[maxn];
int d[maxn];
int p[maxn];
int a[maxn];
void init()
{
	for(int i=0;i<n;i++)
		G[i].clear();
	edges.clear();
}
void AddEdge(int from, int to, int cap, int cost)
{
	edges.push_back(Edge(from,to,cap,0,cost));
	edges.push_back(Edge(to,from,0,0,-cost));
	int M = edges.size();
	G[from].push_back(M-2);
	G[to].push_back(M-1);
}
bool SPFA(int s, int t, int& flow, LL& cost)
{
	for(int i=0;i<=n+1;i++)
 		d[i] = INF;
	memset(inq, 0, sizeof(inq));
	d[s] = 0; inq[s] = 1; p[s] = 0; a[s] = INF;
	queue<int>Q;
	Q.push(s);
	while(!Q.empty())
	{
		int u = Q.front();Q.pop();
		inq[u] = 0;
		for(int i=0;i<G[u].size();i++)
		{
			Edge& e = edges[G[u][i]];
			if(e.cap > e.flow && d[e.to] > d[u] + e.cost)
			{
				d[e.to] = d[u] + e.cost;
				p[e.to] = G[u][i];
				a[e.to] = min(a[u], e.cap - e.flow);
				if(!inq[e.to]){Q.push(e.to);inq[e.to] = 1;}
			}
		}
	}
	if(d[t] == INF) return false;
	flow += a[t];
	cost += (LL) d[t] * (LL) a[t];
	for(int u=t;u!=s;u=edges[p[u]].from)
	{
		edges[p[u]].flow += a[t];
		edges[p[u]^1].flow -= a[t];
	}
	return true;
}
int MincostMaxflow(int s, int t, LL& cost)
{
	int flow = 0; cost = 0;
	while(SPFA(s,t,flow,cost));
	return flow;
}
int N, K;
int W[100][100];
int main()
{
	while(scanf("%d%d", &N, &K)!=EOF)
	{
		for(int i=1;i<=N;i++)
		{
			for(int j=1;j<=N;j++)
			{
				scanf("%d", &W[i][j]);
			}
		}
		n = 2 * N * N + 2;
		init();
		AddEdge(0,1,K,0);
		AddEdge(2*N*N,n-1,INF,0);
		for(int i=1;i<=N;i++)
		{
			for(int j=1;j<=N;j++)
			{
				AddEdge(N*i-N+j,N*i-N+j+N*N,1,-W[i][j]);
				AddEdge(N*i-N+j,N*i-N+j+N*N,INF,0);
			}
		}
		for(int i=1;i<=N;i++)
		{
			for(int j=1;j<=N;j++)
			{
				if(j < N)
				{
					AddEdge(N*i-N+j+N*N, N*i-N+j+1,INF,0);
				}
				if(i < N)
				{
					AddEdge(N*i-N+j+N*N, N*i+j,INF,0);
				}
			}
		}
		LL cost = 0;
		int ans = MincostMaxflow(0,n-1,cost);
		printf("%lld\n", -cost);
	}
	return 0;
}

POJ 3422 kaka's matrix trvals（费用流）

标签：acm

原文地址：http://blog.csdn.net/moguxiaozhe/article/details/43765147