【luogu2756】 飞行员配对方案问题 [二分图匹配 匈牙利算法]

luogu2756

匈牙利 然后输出match就好了
我会说是因为我的最大流写这题写挂了我才来写匈牙利的吗

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
#define Min(x,y) ((x)<(y)?(x):(y))
const int N=200+50,M=30000+5,inf=0x3f3f3f3f,P=19650827;
int n,m,ans=0,match[N];
bool link[N][N],vis[N];
template <class t>void rd(t &x){
    x=0;int w=0;char ch=0;
    while(!isdigit(ch)) w|=ch=='-',ch=getchar();
    while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    x=w?-x:x;
}

bool dfs(int x){
    for(int i=m+1;i<=n;++i)
    if(link[x][i]&&!vis[i]){
        vis[i]=1;
        if(!match[i]||dfs(match[i])){match[i]=x;return 1;}
    }
    return 0;
}

int main(){
    freopen("in2.txt","r",stdin);
    //freopen("xor.out","w",stdout);
    rd(m),rd(n);
    int x,y;
    while(scanf("%d%d",&x,&y)&&(x+y+2)) link[x][y]=1;
    for(int i=1;i<=m;++i){
        memset(vis,0,sizeof(vis));
        if(dfs(i)) ++ans;
    }
    printf("%d\n",ans);
    for(int i=m+1;i<=n;++i)
    if(match[i]) printf("%d %d\n",match[i],i);
    return 0;
}

63昏

#include
   
   
    
    
#include
    
    
     
     
#include
     
     
      
      
#include
      
      
       
       
#include
       
       
         #include 
        
          using namespace std; #define Min(x,y) ((x)<(y)?(x):(y)) const int N=200+50,M=30000+5,inf=0x3f3f3f3f,P=19650827; int n,m,tt,s,t,ans,pre[N],ans1[N],ans2[N]; template 
         
           void rd(t &x){ x=0;int w=0;char ch=0; while(!isdigit(ch)) w|=ch=='-',ch=getchar(); while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar(); x=w?-x:x; } int head[N],tot=1; struct edge{int v,flo,nxt;}e[M<<1]; void add(int u,int v,int flo){ e[++tot]=(edge){v,flo,head[u]},head[u]=tot; e[++tot]=(edge){u,0,head[v]},head[v]=tot; } queue 
          
            q;bool vis[N],used[N]; bool bfs(){ while(!q.empty()) q.pop(); memset(vis,0,sizeof(vis)); q.push(s),vis[s]=1; while(!q.empty()){ int u=q.front();q.pop(); for(int i=head[u],v;i;i=e[i].nxt) if(e[i].flo&&!vis[v=e[i].v]){ q.push(v),pre[v]=i,vis[v]=1; if(v==t) return 1; } } return 0; } void upd(){ int x=t; while(x!=s){ int i=pre[x]; --e[i].flo,++e[i^1].flo; if(!used[x]){ if(x<=m&&x) ans1[++ans1[0]]=x,used[x]=1; if(x>m&&x<=n) ans2[++ans2[0]]=x,used[x]=1; } x=e[i^1].v; } ++ans; } int main(){ // freopen("in2.txt","r",stdin); //freopen("xor.out","w",stdout); rd(m),rd(n);s=n+1,t=s+1; int x,y;ans=ans1[0]=ans2[0]=0; while(scanf("%d%d",&x,&y)!=EOF&&(x+y+2)) add(x,y,1); for(int i=1;i<=m;++i) add(s,i,1); for(int i=m+1;i<=n;++i) add(i,t,1); while(bfs()) upd(); printf("%d\n",ans); for(int i=1;i<=ans;++i) printf("%d %d\n",ans1[i],ans2[i]); return 0; }