poj 1459 最大流

#include "stdio.h" //poj 1459 最大流
#include "string.h"
#include "queue"
using namespace std;

#define N 205
#define INF 0x3fffffff

int n;
bool mark;
int map[N][N],maxf[N],route[N];

int EK();
int BFS();
void init();
int MIN(int x,int y);

int main()
{
	int i,j;
	char ch;
	int m,np,nc;
	int u,v,w;
	while(scanf("%d%d%d%d",&n,&np,&nc,&m)!=-1)
	{
		init();
		while(m--)
		{
			scanf(" (%d,%d)%d",&u,&v,&w);
			if(u==v) continue;
			map[u+1][v+1] += w;
		}
		int start = 0;  //超级源点
		while(np--)
		{
			scanf(" (%d)%d",&v,&w);
			map[start][v+1] += w;
		}
		int end = n+1;  //超级汇点
		while(nc--)
		{
			scanf(" (%d)%d",&u,&w);
			map[u+1][end] += w;
		}
		int ans = EK();
		printf("%d
",ans);
	}
	return 0;
}

void init(){	memset(map,0,sizeof(map));	}
int MIN(int x,int y) {	 return x<y?x:y;	}

int EK()
{
	int ans=0,kejia;
	int x,y;
	while(kejia = BFS())
	{
		ans += kejia;
		y = n+1;
		while(y!=0)
		{
			x = route[y];
			map[x][y]-=kejia;
			map[y][x]+=kejia;
			y = x;
		}
	}
	return ans;
}

int BFS()
{
	int i;
	int x,y;
	memset(route,-1,sizeof(route));
	for(i=0;i<N;i++) maxf[i] = INF;
	queue<int> q;
	route[0] = 0;
	q.push(0);
	while(!q.empty())
	{
		x = q.front();
		q.pop();
		for(y=0;y<=n+1;y++)
		{
			if(route[y]==-1 && map[x][y]!=0)
			{
				maxf[y] = MIN(maxf[x],map[x][y]);
				route[y] = x;
				q.push(y);
			}
		}
	}
	if(route[n+1]==-1) return 0;
	return maxf[n+1];
}

原文地址:https://www.cnblogs.com/ruo-yu/p/4411998.html