max_flow模板(POJ 1273)

C++ code:

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

long max_flow();
int M;
long mat[201][201], d[201];

int main()
{
	int N, i, S, E;
	long C;

	while(scanf("%d%d", &N, &M) == 2)
	{
		memset(mat, 0, sizeof(mat));
		mat[0][1] = d[0] = 200000000;
		for(i = 1; i <= N; i++)
		{
			scanf("%d%d%ld", &S, &E, &C);
			mat[S][E] += C;
		}
		printf("%ld\n", max_flow());
	}

	return 0;
}

long max_flow()
{
	long flow[201][201], j;
	int i, pre[201], p, q, t, que[201];

	memset(flow, 0, sizeof(flow));
	for(;;)
	{
		for(i = p = q = t = 0; i <= M; pre[i++] = -1);
		for(; p <= q && pre[M] == -1; t = que[++p])
			for(i = 1; i <= M; i++)
				if((j = mat[t][i] - flow[t][i]) && pre[i] == -1)
				{
					pre[que[++q] = i] = t;
					d[i] = d[t] < j ? d[t] : j;
				}
				else if((j = flow[i][t]) && pre[i] == -1)
				{
					pre[que[++q] = i] = -t;
					d[i] = d[t] < j ? d[t] : j;
				}
		if(p > q)
			break;
		for(i = M; i;)
			if(pre[i] >= 0)
			{
				flow[pre[i]][i] += d[M];
				i = pre[i];
			}
			else if(pre[i] < 0)
			{
				flow[i][-pre[i]] -= d[M];
				i = -pre[i];
			}
	}

	return flow[0][1];
}