Courses
http://acm.hdu.edu.cn/showproblem.php?pid=1083
題意:有p門的課,每門課都有若干學生,現在要為每個課程分配一名課代表,每個學生只能擔任一門課的課代表,如果每個課都能找到課代表,則輸出"YES",否則"NO"。
題解:二分圖匹配
?
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int #define endl "\n" using namespace std; typedef long long ll; //typedef __int128 lll; const int N=1000+10; const int M=100000+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,p,l,r,u,v; int ans,cnt,flag,temp,sum; int mp[N][N]; bool vis[N]; int match[N]; char str; struct node{};bool dfs(int u){//cout<<u<<endl;for(int i=1;i<=n;i++){if(vis[i]==0&&mp[u][i]){vis[i]=1;if(match[i]==-1||dfs(match[i])){match[i]=u;return 1;}}}return 0; }void maxmatch(){for(int i=1;i<=p;i++){memset(vis,0,sizeof(vis));if(!dfs(i))break;ans++;} } void init(){memset(mp,0,sizeof(mp));memset(match,-1,sizeof(match));ans=0; } int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endif//ios::sync_with_stdio(false);//cin.tie(0);//cout.tie(0);scanf("%d",&t);while(t--){scanf("%d%d",&p,&n);init();for(int i=1;i<=p;i++){scanf("%d",&k);for(int j=1;j<=k;j++){scanf("%d",&v);mp[i][v]=1;}}maxmatch();//cout<<ans<<endl;if(ans==p){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}}#ifdef DEBUGprintf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC); #endif//cout << "Hello world!" << endl;return 0; }?
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