poj 3422

#include "stdio.h"  //额，按最小费用最大流的模板来的！poj 3422
#include "string.h"
#include "queue"
using namespace std;

#define N 5005
#define INF 0x3fffffff

struct node{
	int u,v,w,k;
	int next;
}edge[4*N];

int n,ans,idx;
bool mark[N];
int dis[N],route[N],head[N];

void init();
void EK(int start,int end);
bool SPFA(int start,int end);
void adde(int u,int v,int w,int k);
void addedge(int u,int v,int w,int k);


int main()
{
	int esp;
	int i,j;
	int x,y,w,k;
	while(scanf("%d %d",&n,&esp)!=-1)
	{
		init();
		k=n*n;
		for(i=1;i<=n;i++)
		{
			for(j=1;j<=n;j++)
			{
				scanf("%d",&w);
				x = (i-1)*n+j;
				adde(x,x+k,-w,1);
				adde(x,x+k,0,esp-1);
				if(j!=n) adde(x+k,x+1,0,esp);
				if(i!=n) adde(x+k,x+n,0,esp);
			}
		}
		int start=0,end=2*n*n+1;
		adde(start,1,0,esp);
		adde(2*k,end,0,esp);
		while(SPFA(start,end))	EK(start,end);
		printf("%d
",-ans);
	}
	return 0;
}

void init()
{
	idx = 0;
	ans = 0;
	memset(head,-1,sizeof(head));
}

void adde(int u,int v,int w,int k)
{
	addedge(u,v,w,k);
	addedge(v,u,-w,0);
}

void addedge(int u,int v,int w,int k)
{
	edge[idx].u = u;
	edge[idx].v = v;
	edge[idx].w = w;
	edge[idx].k = k;
	edge[idx].next = head[u];
	head[u] = idx;
	idx++;
}

bool SPFA(int start,int end)
{
	int i;
	int x,y;
	memset(route,-1,sizeof(route));
	memset(mark,false,sizeof(mark));
	for(i=0;i<N;i++)	dis[i] = INF;
	dis[0] = 0;
	queue<int> q;
	q.push(start);
	mark[start] = true;
	while(!q.empty())
	{
		x = q.front();
		q.pop();
		for(i=head[x];i!=-1;i = edge[i].next)
		{
			y = edge[i].v;
			if(edge[i].k && dis[y]>dis[x]+edge[i].w)
			{
				dis[y] = dis[x] + edge[i].w;
				route[y] = i;
				if(mark[y]==false)
				{
					mark[y] = true;
					q.push(y);
				}
			}
		}
		mark[x] = false;
	}
	if(route[end]==-1) return false;
	return true;
}

void EK(int start,int end)
{
	int x,y;
	y = route[end];
	while(y!=-1)
	{
		x = y^1;
		ans += edge[y].w;
		edge[y].k--;
		edge[x].k++;
		y = route[edge[y].u];
	}
}