【HDU】4876 ZCC loves cards 暴力

传送门：【HDU】4876 ZCC loves cards

题目分析：

这题无力吐嘈。。。。能想到的优化都用上吧。。。

代码如下：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std ;

#define REP( i , n ) for ( int i = 0 ; i < n ; ++ i )
#define REPF( i , a , b ) for ( int i = a ; i <= b ; ++ i )
#define REPV( i , a , b ) for ( int i = a ; i >= b ; -- i )
#define CLR( a , x ) memset ( a , x , sizeof a )

const int MAXN = 40000 ;

int n , K ;
int card[25] ;
int a[6] ;
int A[MAXN][6] ;
int cnt ;
int vis[130] ;
int G[6][6] ;
int L ;
int ans ;
int Time ;
int b[MAXN] ;
int c[7][2] ;

void dfs ( int cur , int j ) {
	if ( cur == K ) {
		REP ( i , K )
			A[cnt][i] = a[i] ;
		++ cnt ;
		return ;
	}
	REPF ( i , j , n - 1 ) {
		a[cur] = card[i] ;
		dfs ( cur + 1 , i + 1 ) ;
	}
}

int better ( int o ) {
	++ Time ;
	int top = 0 , tmp ;
	b[top ++] = 0 ;
	REP ( i , K ) {
		tmp = top ;
		REP ( j , top )
			b[tmp ++] = A[o][i] ^ b[j] ;
		top = tmp ;
	}
	REP ( i , top )
		vis[b[i]] = Time ;
	REPF ( i , L , ans + 1 )
		if ( vis[i] != Time )
			return 0 ;
	return 1 ;
}

void dfs3 ( int N , int cur ) {
	if ( cur == K ) {
		++ Time ;
		int x = 0 ;
		REP ( i , K )
			x ^= a[i] ;
		REP ( i , K ) {
			int y = 0 ;
			REPF ( j , i , K - 1 ) {
				y ^= a[j] ;
				vis[y] = Time ;
				vis[x ^ y] = Time ;
			}
		}
		int tot = L - 1 ;
		while ( vis[tot + 1] == Time )
			++ tot ;
		if ( tot >= L )
			ans = max ( ans , tot ) ;
		return ;
	}
	REPF ( i , 1 , N )
		if ( c[i][1] ) {
			-- c[i][1] ;
			a[cur] = c[i][0] ;
			dfs3 ( N , cur + 1 ) ;
			++ c[i][1] ;
		}
}

void solve () {
	cnt = 0 ;
	REP ( i , n )
		scanf ( "%d" , &card[i] ) ;
	sort ( card , card + n ) ;
	dfs ( 0 , 0 ) ;
	CLR ( vis , 0 ) ;
	Time = 0 ;
	ans = 0 ;
	REP ( i , cnt ) {
		if ( !better ( i ) )
			continue ;
		int tot = 0 ;
		REP ( j , K ) {
			if ( !j || A[i][j] != A[i][j - 1] ) {
				c[++ tot][0] = A[i][j] ;
				c[tot][1] = 0 ;
			}
			++ c[tot][1] ;
		}
		a[0] = c[1][0] ;
		-- c[1][1] ;
		dfs3 ( tot , 1 ) ;
	}
	printf ( "%d\n" , ans ) ;
}

int main () {
	while ( ~scanf ( "%d%d%d" , &n , &K , &L ) )
		solve () ;
	return 0 ;
}