hdu 1532 Drainage Ditches(最大流)

題目：

鏈接：點擊打開鏈接

題意：

求最大流速。

思路：

Edmond_karp就行。

代碼：

#include 
#include 
#include 
#include 
using namespace std;
#define INF 100000000

const int N = 220;

int cap[N][N],flow[N][N];
int a[N];
int n,m;
int s,e,c;

void edmonds_karp(int s,int t)
{
    queue q;
    memset(flow,0,sizeof(flow));
    int f = 0;
    int p[N];
    for(;;)
    {
        memset(a,0,sizeof(a));
        a[s] = INF;
        q.push(s);
        while(!q.empty())
        {
            int u = q.front();
            q.pop();
            for(int v=1; v<=n; v++)
            {
                if(!a[v] && cap[u][v] > flow[u][v])
                {
                    p[v] = u;
                    q.push(v);
                    a[v] = a[u] < cap[u][v] - flow[u][v] ? a[u] : cap[u][v] - flow[u][v];
                }
            }
        }
        if(a[t] == 0)
            break;
        for(int u=t; u!=s; u=p[u])
        {
            flow[p[u]][u] += a[t];
            flow[u][p[u]] += a[t];
        }
        f += a[t];
    }
    printf("%d\n",f);
}

int main()
{
    //freopen("input.txt","r",stdin);
    while(scanf("%d%d",&n,&m) != EOF)
    {
        memset(cap,0,sizeof(cap));
        for(int i=0; i


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收獲：
------>增廣路算法，Edmond_karp模板：

queue q;
    memset(flow,0,sizeof(flow));
    int f = 0;
    int p[N];
    for(;;)
    {
        memset(a,0,sizeof(a));
        a[s] = INF;
        q.push(s);
        while(!q.empty())
        {
            int u = q.front();
            q.pop();
            for(int v=1; v<=n; v++)
            {
                if(!a[v] && cap[u][v] > flow[u][v])
                {
                    p[v] = u;
                    q.push(v);
                    a[v] = a[u] < cap[u][v] - flow[u][v] ? a[u] : cap[u][v] - flow[u][v];
                }
            }
        }
        if(a[t] == 0)
            break;
        for(int u=t; u!=s; u=p[u])
        {
            flow[p[u]][u] += a[t];
            flow[u][p[u]] += a[t];
        }
        f += a[t];
    }


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戰斗，從不退縮；奮斗，永不停歇~~~~~~~~~~~~~