UVa 753 (二分图最大匹配) A Plug for UNIX

  1 #include <bits/stdc++.h>
  2 
  3 using namespace std;
  4 
  5 const int maxn = 400 + 10;
  6 
  7 vector<string> names;
  8 int ID(const string& s)
  9 {
 10     for(int i = 0; i < names.size(); ++i)
 11         if(names[i] == s) return i;
 12     names.push_back(s);
 13     return names.size() - 1;
 14 }
 15 
 16 int n, m, k;
 17 bool d[maxn][maxn];
 18 int target[maxn], device[maxn];
 19 
 20 const int INF = 1000000000;
 21 
 22 struct Edge
 23 {
 24     int from, to, cap, flow;
 25     Edge(int u=0, int v=0, int c=0, int f=0):from(u), to(v), cap(c), flow(f) {}
 26 };
 27 
 28 struct EdmondsKarp
 29 {
 30     int n, m;
 31     vector<Edge> edges;
 32     vector<int> G[maxn];
 33     int a[maxn];
 34     int p[maxn];
 35 
 36     void Init(int n)
 37     {
 38         for(int i = 0; i < n; ++i) G[i].clear();
 39         edges.clear();
 40     }
 41 
 42     void AddEdge(int from, int to, int cap)
 43     {
 44         edges.push_back(Edge(from, to, cap, 0));
 45         edges.push_back(Edge(to, from, 0, 0));
 46         m = edges.size();
 47         G[from].push_back(m-2);
 48         G[to].push_back(m-1);
 49     }
 50 
 51     int MaxFlow(int s, int t)
 52     {
 53         int flow = 0;
 54         for(;;)
 55         {
 56             memset(a, 0, sizeof(a));
 57             queue<int> Q;
 58             Q.push(s);
 59             a[s] = INF;
 60             while(!Q.empty())
 61             {
 62                 int x = Q.front(); Q.pop();
 63                 for(int i = 0; i < G[x].size(); ++i)
 64                 {
 65                     Edge& e = edges[G[x][i]];
 66                     if(!a[e.to] && e.cap > e.flow)
 67                     {
 68                         p[e.to] = G[x][i];
 69                         a[e.to] = min(a[x], e.cap - e.flow);
 70                         Q.push(e.to);
 71                     }
 72                 }
 73                 if(a[t]) break;
 74             }
 75             if(!a[t]) break;
 76             for(int u = t; u != s; u = edges[p[u]].from)
 77             {
 78                 edges[p[u]].flow += a[u];
 79                 edges[p[u]^1].flow -= a[u];
 80             }
 81             flow += a[t];
 82         }
 83         return flow;
 84     }
 85 };
 86 
 87 EdmondsKarp g;
 88 
 89 int main()
 90 {
 91     //freopen("in.txt", "r", stdin);
 92     int T;
 93     scanf("%d", &T);
 94     while(T--)
 95     {
 96         names.clear();
 97         memset(d, 0, sizeof(d));
 98         string s1, s2;
 99         scanf("%d", &n);
100         for(int i = 0; i < n; ++i) { cin >> s1; target[i] = ID(s1); }
101         scanf("%d", &m);
102         for(int i = 0; i < m; ++i) { cin >> s1 >> s2; device[i] = ID(s2); }
103         scanf("%d", &k);
104         for(int i = 0; i < k; ++i) { cin >> s1 >> s2; d[ID(s1)][ID(s2)] = true;    }
105         //Floyd
106         int V = names.size();
107         for(int k = 0; k < V; ++k)
108             for(int i = 0; i < V; ++i)
109                 for(int j = 0; j < V; ++j)
110                     d[i][j] |= d[i][k] && d[k][j];
111 
112         //Build Graph
113         g.Init(V+2);
114         for(int i = 0; i < m; ++i) g.AddEdge(V, device[i], 1);//源点到每个设备
115         for(int i = 0; i < n; ++i) g.AddEdge(target[i], V+1, 1);//每个插座到汇点
116         for(int i = 0; i < m; ++i)
117             for(int j = 0; j < n; ++j)
118                 if(d[device[i]][target[j]]) g.AddEdge(device[i], target[j], INF);
119         int ans = g.MaxFlow(V, V+1);
120         printf("%d\n", m-ans);
121         if(T) puts("");
122     }
123 
124     return 0;
125 }