题解 【重庆八中模拟赛】寻找代表元

#include<bits/stdc++.h>
using namespace std;
 
inline int read(){
    int sum=0,f=1;char ch=getchar();
    while(ch>‘9‘ || ch<‘0‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘ && ch<=‘9‘){sum=sum*10+ch-‘0‘;ch=getchar();}
    return f*sum;
}
 
struct road{
    int next,to;
}e[100001];
int n,m;
int head[100001],cnt=0;
int linker[100001],vis[100001];
 
void add(int x,int y){
    e[++cnt].to=head[x];
    e[cnt].next=y;
    head[x]=cnt;
}
 
bool dfs(int x){
    for(int i=head[x];i;i=e[i].to){
        int k=e[i].next;
        if(vis[k]) continue;
        vis[k]=1;
        if(linker[k]==-1||dfs(linker[k])){
            linker[k]=x;
            return 1;
        }
    }
    return 0;
}
 
int hungarian(int m){
    int ans=0;
    for(int i=0;i<=m+n;i++) linker[i]=-1;
    for(int i=1;i<=m;i++){
        memset(vis,0,sizeof(vis));
        if(dfs(i)) ans++;
        //    cout<<"ok"<<endl;
    }
    return ans;
}
 
int main(){
    n=read();m=read();
    int x;
    for(int i=1;i<=n;i++){
        while(scanf("%d",&x)!=EOF&&x!=0)   
                      add(x,i+m),add(i+m,x);
        
    }
    printf("%d\n",hungarian(m));
    return 0;
}