【网络流24题】搭配飞行员(飞行员配对方案问题)

 1 #include<cstring>
 2 #include<cmath>
 3 #include<iostream>
 4 #include<algorithm>
 5 #include<cstdio>
 6 #include<queue>
 7 
 8 #define N 207
 9 #define INF 10000007
10 using namespace std;
11 inline int read()
12 {
13     int x=0,f=1;char ch=getchar();
14     while(ch<‘0‘||ch>‘9‘){if (ch==‘-‘) f=-1;ch=getchar();}
15     while(ch>=‘0‘&&ch<=‘9‘){x=(x<<3)+(x<<1)+ch-‘0‘;ch=getchar();}
16     return f*x;
17 }
18 
19 int n,m,S,T,ans;
20 int cnt=1,head[N],rea[N*N],val[N*N],next[N*N];
21 int dis[N];
22 
23 void add(int u,int v,int fee)
24 {
25     next[++cnt]=head[u],head[u]=cnt;
26     rea[cnt]=v,val[cnt]=fee;
27 }
28 bool bfs()
29 {
30     for (int i=1;i<=T;i++)dis[i]=0;
31     queue<int>q;q.push(S);
32     dis[S]=1;
33     while(!q.empty())
34     {
35         int u=q.front();q.pop();
36         for (int i=head[u];i!=-1;i=next[i])
37         {
38             int v=rea[i],fee=val[i];
39             if (!dis[v]&&fee>0)
40             {
41                 dis[v]=dis[u]+1;
42                 if (v==T) return 1;
43                 q.push(v);
44             }
45         }
46     }
47     return 0;
48 }
49 int dfs(int u,int MF)
50 {
51     int res=0;
52     if (u==T||MF==0) return MF;
53     for (int i=head[u];i!=-1;i=next[i])
54     {
55         int v=rea[i],fee=val[i];
56         if (dis[v]!=dis[u]+1) continue;
57         int x=dfs(v,min(MF,fee));
58         if (x)
59         {
60             val[i]-=x,val[i^1]+=x;
61             MF-=x,res+=x;
62             if (res==MF) return res;
63         }
64     }
65     if (!res) dis[u]=0;
66     return res;
67 }
68 void Dinic()
69 {
70     while(bfs())
71     {
72         int x=dfs(S,INF);
73         while(x)
74         {
75             ans+=x;
76             x=dfs(S,INF);
77         }
78     }
79 }
80 int main()
81 {
82     memset(head,-1,sizeof(head));
83     n=read(),m=read();
84     int x=read(),y=read();
85     while(x!=-1||y!=-1)
86     {
87         add(x,y,1),add(y,x,0);
88         x=read(),y=read();
89     }
90     S=n+m+1,T=n+m+2;
91     for (int i=1;i<=n;i++) add(S,i,1),add(i,S,0);
92     for (int i=n+1;i<=n+m;i++) add(i,T,1),add(T,i,0);
93     Dinic();
94     if (!ans) printf("No Solution!\n");
95     else printf("%d",ans);
96 }