JZOI1062 【USACO2013JAN】invite

#include <bits/stdc++.h>
#define ll long long
#define INF 2147483647
#define ll_INF 9223372036854775807
using namespace std;
inline int read() {
    int x = 0,tmp = 1;char ch = getchar();
    while( ch < '0' || ch > '9' ) {if ( ch == '-' ) tmp = -1; ch = getchar();}
    while( ch >= '0' && ch <= '9'){x = x * 10 + ch - '0'; ch = getchar(); }
    return x * tmp;
}
multiset< int >_group[25100];
queue< int > Q;
bool _flag[1100000];
int main() {
    memset( _flag, 0, sizeof( _flag ) );
    int N = read(), G = read();
    for( int i = 1 ; i <= G ; ++ i ) {
        int k = read();
        for( int j = 1 ; j <= k; ++ j ) _group[i].insert( read() );
    }
    Q.push( 1 );
    int tot = 1;
    _flag[1] = 1;
    while( !Q.empty() ) {
        int _now = Q.front();
        Q.pop();
        for( int i = 1 ; i <= G ; ++ i ) if( !_group[i].empty() ) {
            auto _where = _group[i].lower_bound( _now );
            if( *_where != _now ) continue; else _group[i].erase( _where );
            if( _group[i].size() == 1 ) {
                auto the_only = _group[i].begin();
                Q.push( *the_only );
                if( !_flag[(int)*the_only] ) tot ++, _flag[(int)*the_only] = 1;
                _group[i].erase( *the_only );
            }
        }
    }
    printf( "%d\n", tot );

    return 0;
}

转载于:https://www.cnblogs.com/ARZhu-NOIpAK/p/6636439.html