Network-Flow

//Created by pritry
int graph[MAX][MAX]; //原图
int source;          //起点，这里为0
int sink;            //终点，这里为n-1
int e[MAX];          //余流
int h[MAX];          //高度
int n;               //顶点数
struct Label
{
    int index;
    friend bool operator < (const Label& a, const Label& b)
    {
        return h[a.index] > h[b.index];
    }
};
void Push(int u, int v)
{
    int df = min(e[u], graph[u][v]);
    graph[u][v] -= df;
    graph[v][u] += df;
    e[u] -= df;
    e[v] += df;
}
void Relabel(int u)
{
    int min_h = INF;
    for(int i = 0; i < n; ++i)
    {
        if(graph[u][i] && h[i] < min_h)
        {
            min_h = h[i];
        }
    }
    h[u] = min_h + 1;
}
int HLPP()
{
    int i;
    Label l;
    priority_queue<Label> Q;
    memset(e, 0, sizeof(e));
    memset(h, 0, sizeof(h));
    h[source] = n;
    for(i = 0; i < n; ++i)
    {
        if(graph[source][i])
        {
            int df = graph[source][i];
            e[source] -= df;
            e[i] += df;
            graph[source][i] -= df;
            graph[i][source] += df;
            l.index = i;
            if(i != source && i != sink) Q.push(l);
        }
    }
    while(!Q.empty())
    {
        l = Q.top();
        Q.pop();
        int u = l.index;
        while(e[u])
        {
            for(i = 0; i < n; ++i)
                if(graph[u][i] && h[u] > h[i])
                    break;

            if(i == n) Relabel(u);

            for(i = 0; i < n; ++i)
            {
                if(h[u] == h[i] + 1 && graph[u][i])
                {
                    Push(u, i);
                    l.index = i;
                    if(e[i] > 0 && i != source && i != sink) Q.push(l);
                }
            }
        }
    }
    return e[sink];
}