Edmonds-Karp算法

建立在Ford-Fulkerson 方法上的增广路算法,与一般的Ford-Fulkerson 算法不同的是,它用广度搜索实现对增广路的寻找

/************************************************************************/
/* Name: maxflow
/* Description: find the max flow of the network from s to t using 
                Edmonds-Karp Algorithm
/* Parameter list: s - begin point of the network
/*                   t - end point of the network
/************************************************************************/
#define MAX_VECT 105
#define INF 105
int c[MAX_VECT][MAX_VECT];
int n;
int maxflow(int s, int t)
{
    int u, v, bg, ed, minflow, flow = 0;
    int queue[MAX_VECT], pre[MAX_VECT];
    while (true)
    {
        memset(pre, -1, sizeof(pre));
        for (queue[bg=ed=0]=s; bg <= ed; bg++)
        {
            u = queue[bg];
            for (int i = 0; (i < n)&&(pre[t]==-1); i++)
                if (c[u][i] > 0 && pre[i] == -1)
                {
                    pre[i] = u;
                    queue[++ed] = i;
                }
        }
        if (pre[t] == -1)break;
        minflow = INF;
        for (u = pre[v=t];v!=s;v=u,u=pre[v])
            if (c[u][v] < minflow) minflow = c[u][v];
        for (u = pre[v=t];v!=s;v=u,u=pre[v])
            c[u][v] -= minflow, c[v][u] += minflow;
        flow += minflow;
    }
    return flow;
}