【PowerOJ1736&网络流24题】飞行员配对方案问题（最小割）

题意：

n<=100，要求输出方案

思路：准备把没刷的24题从头搞一遍

输出方案的话就在增广的时候记一下另一端的编号就好

 #include<bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef long double ld;
 typedef pair<int,int> PII;
 typedef pair<ll,ll> Pll;
 typedef vector<int> VI;
 typedef vector<PII> VII;
 //typedef pair<ll,ll>P;
 #define N  300010
 #define M  200010
 #define INF 1e9
 #define fi first
 #define se second
 #define MP make_pair
 #define pb push_back
 #define pi acos(-1)
 #define mem(a,b) memset(a,b,sizeof(a))
 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)
 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)
 #define lowbit(x) x&(-x)
 #define Rand (rand()*(1<<16)+rand())
 #define id(x) ((x)<=B?(x):m-n/(x)+1)
 #define ls p<<1
 #define rs p<<1|1

 const ll MOD=1e9+,inv2=(MOD+)/;
       double eps=1e-;
       int dx[]={-,,,};
       int dy[]={,,-,};

 int head[N],vet[N],len[N],nxt[N],dis[N],gap[N],x[N],y[N],f[N],s,S,T,tot;

 int read()
 {
    int v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();
    return v*f;
 }

 void add(int a,int b,int c)
 {
     nxt[++tot]=head[a];
     vet[tot]=b;
     len[tot]=c;
     head[a]=tot;

     nxt[++tot]=head[b];
     vet[tot]=a;
     len[tot]=;
     head[b]=tot;
 }

 int dfs(int u,int aug)
 {
     if(u==T) return aug;
     int e=head[u],val=s-,flow=;
     while(e)
     {
         int v=vet[e];
         if(len[e])
         {
             if(dis[u]==dis[v]+)
             {
                 int t=dfs(v,min(len[e],aug-flow));
                 if(t) f[u]=v;
                 len[e]-=t;
                 len[e^]+=t;
                 flow+=t;
                 if(dis[S]>=s) return flow;
                 if(aug==flow) break;
             }
             val=min(val,dis[v]);
         }
         e=nxt[e];
     }
     if(!flow)
     {
         gap[dis[u]]--;
         if(!gap[dis[u]]) dis[S]=s;
         dis[u]=val+;
         gap[dis[u]]++;
     }
     return flow;
 }

 int maxflow()
 {
     rep(i,,s) gap[i]=;
     rep(i,,s) dis[i]=;
     gap[]=s;
     int ans=;
     while(dis[S]<s) ans+=dfs(S,INF);
     return ans;
 }

 int main()
 {
     //freopen("1.in","r",stdin);
     int m=read(),n=read();
     rep(i,,n) head[i]=;
     tot=;
     int l=;
     while()
     {
         l++;
         x[l]=read(),y[l]=read();
         if(x[l]==-) break;
         add(x[l],y[l],);
     }
     s=n+m;
     S=++s;
     T=++s;
     rep(i,,m) add(S,i,);
     rep(i,m+,n) add(i,T,);
     int ans=maxflow();
     if(ans==)
     {
         printf("No Solution!\n");
         return ;
     }
     printf("%d\n",ans);
     rep(i,,m)
      if(f[i]) printf("%d %d\n",i,f[i]);

     return ;
 }