【HDU】5321 Beautiful Set【枚举k求贡献，欧拉函数应用】

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传送门：【HDU】5321 Beautiful Set

$my~~code:$

#include <stdio.h>
#include <string.h>
#include <vector>
#include <algorithm>
using namespace std ;typedef long long LL ;#define clr( a , x ) memset ( a , x , sizeof a )const int MAXN = 100005 ;
const int mod = 258280327 ;bool prime[MAXN] ;
int phi[MAXN] ;
int cnt[MAXN] ;
int id[MAXN] ;
int f[MAXN] ;
int vf[MAXN] ;
int n ;void exgcd ( int a , int b , int& x , int& y ) {if ( b ) {exgcd ( b , a % b , y , x ) ;y -= a / b * x ;} else x = 1 , y = 0 ;
}int inv ( int a ) {int x , y , b = mod ;exgcd ( a , b , x , y ) ;if ( x < 0 ) x += mod ;return x ;
}int cmp ( int a , int b ) {return cnt[a] > cnt[b] ;
}void calc () {for ( int i = 1 ; i < MAXN ; ++ i ) {id[i] = i ;for ( int j = i + i ; j < MAXN ; j += i ) {cnt[i] += cnt[j] ;}}sort ( id + 1 , id + MAXN , cmp ) ;
}void preprocess () {f[0] = vf[0] = 1 ;for ( int i = 1 ; i < MAXN ; ++ i ) {phi[i] = i ;f[i] = ( LL ) i * f[i - 1] % mod ;vf[i] = inv ( f[i] ) ;}for ( int i = 2 ; i < MAXN ; ++ i ) if ( !prime[i] ) {for ( int j = i ; j < MAXN ; j += i ) {phi[j] = phi[j] / i * ( i - 1 ) ;prime[j] = 1 ;}}
}int c ( int a , int b ) {return ( LL ) f[a] * vf[b] % mod * vf[a - b] % mod ;
}void solve () {int x ;int ans1 = 0 , ans2 = 0 ;clr ( cnt , 0 ) ;for ( int i = 1 ; i <= n ; ++ i ) {scanf ( "%d" , &x ) ;cnt[x] ++ ;}calc () ;for ( int i = 1 ; i < MAXN ; ++ i ) {int tmp = 0 ;for ( int j = 1 ; j < MAXN ; ++ j ) {int idx = id[j] ;if ( cnt[idx] < i ) break ;int t = ( LL ) c ( cnt[idx] , i ) * phi[idx] % mod ;tmp = ( tmp + t ) % mod ;}ans2 = ( ans2 + ( LL ) i * tmp ) % mod ;tmp = ( LL ) tmp * f[i] % mod * f[n - i + 1] % mod ;ans1 = ( ans1 + tmp ) % mod ;}if ( ans1 > ans2 ) printf ( "Mr. Zstu %d\n" , ans1 ) ;else if ( ans1 < ans2 ) printf ( "Mr. Hdu %d\n" , ans2 ) ;else printf ( "Equal %d\n" , ans1 ) ;
}int main () {preprocess () ;while ( ~scanf ( "%d" , &n ) ) solve () ;return 0 ;
}