UVA 753 A Plug for UNIX

最新推荐文章于 2025-09-13 12:59:37 发布

转载最新推荐文章于 2025-09-13 12:59:37 发布 · 83 阅读

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原文链接：http://www.cnblogs.com/Commence/p/4020608.html

本文介绍了一种使用最大流算法解决设备与插头匹配问题的方法，通过建立源点到设备、设备到插头再到汇点的网络模型，实现对设备插头最优配置的计算。

最大流解决。

设置源点 0，连接所有设备（device）。设备-插头 -汇点

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 330
const int INF = 0x3f3f3f3f ;
int N,M,K,src,tag;
int p[MAXN];
int flow[MAXN][MAXN],cap[MAXN][MAXN];
int a[MAXN];
map<string ,int > cz,deg;
string str;
void read()
{
    cin >> N;
    int add = 0;
    cz.clear(); deg.clear();
    memset(cap,0,sizeof(cap));
    for (int i = 1; i <= N; i++)
    {
        cin >> str;
        cz[str] = i;
    }
    cin >> M;
    for (int i = 1; i <= M; i++)
    {
        cin >> str;
        deg[str] = i;
        cap[0][i] += 1;
        cin >> str;
        int tmp = cz[str];
        if (tmp == 0)//需要新的插座
        {
            add ++;
            cz[str] = N + add;
            tmp = N + add;
        }
        cap[i][tmp + M] += 1;
    }
    for (int i = M + 1; i <= M + N; i++)
        cap[i][N + M + add + 1] += 1;
    src = 0; tag = N + M + add + 1;
    cin >> K;
    while (K --)
    {
        cin >> str;
        int tmp = cz[str];
        cin >> str;
        int res = cz[str];
        cap[M + tmp][M + res] += INF;
    }
}
int Edmonds_karp()
{
    memset(flow,0,sizeof(flow));
    queue<int>q;
    int ans = 0;
    while (!q.empty()) q.pop();
    while (true)
    {
        memset(a,0,sizeof(a));
        a[src] = INF;
        q.push(src);
        while (!q.empty())
        {
            int u = q.front(); q.pop();
            for (int v = 1; v <= tag; v++)
                if (!a[v] && cap[u][v] > flow[u][v])
            {
                p[v] = u;
                q.push(v);
                a[v] = min (a[u],cap[u][v] - flow[u][v]);
            }
        }
        if (a[tag] == 0) break;
        for (int u = tag; u != src; u = p[u])
        {
            flow[p[u]][u] += a[tag];
            flow[u][p[u]] -= a[tag];
        }
        ans += a[tag];
    }
    return ans;
}
int main()
{
    //freopen("sample.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while (T--)
    {
        read();
        printf("%d\n",M - Edmonds_karp());
        if (T) putchar('\n');
    }
    return 0;
}