mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<algorithm>
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#include<vector>
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using namespace std ;
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int son[11111] ;
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int chain[10][1111] , a[11111] ;
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int vis[11111] , du[11111] , len[11] ;
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double dfs ( int u , int step , int c ) {
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chain[c][step] = a[u] ;
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if ( son[u] == -1 ) return step + 2 ;
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return dfs ( son[u] , step + 1 , c ) ;
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}
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int main () {
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int n , m ;
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int T ;
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scanf ( "%d" , &T ) ;
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while ( T -- ) {
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scanf ( "%d%d" , &n , &m ) ;
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memset ( chain , 0 , sizeof ( chain ) ) ;
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memset ( du , 0 , sizeof ( du ) ) ;
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memset ( son , -1 , sizeof ( son ) ) ;
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for ( int i = 0 ; i < n ; i ++ )
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scanf ( "%d" , &a[i] ) ;
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for ( int i = 1 ; i <= m ; i ++ ) {
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int a , b ;
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scanf ( "%d%d" , &a , &b ) ;
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son[a] = b ;
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du[b] ++ ;
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}
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double sum = 1 , ans = 0 ;
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int tot = 0 ;
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for ( int i = 0 ; i < n ; i ++ ) {
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if ( du[i] == 0 ) {
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len[tot] = dfs ( i , 0 , tot ) ;
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sum *= len[tot] ;
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len[tot] -- ;
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tot ++ ;
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}
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}
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sum -= 1 ;
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for ( int i = 0 ; i < 1000 ; i ++ ) {
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for ( int j = 0 ; j < 1 << tot ; j ++ ) {
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int flag = 0 ;
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double add = 0 , p = 1 , x = 0 , cnt = 0 ;
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for ( int k = 0 ; k < tot ; k ++ ) {
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if ( chain[k][i] ) cnt ++ ;
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if ( j & (1<<k) ) {
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if ( chain[k][i] == 0 ) {
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flag = 1 ;
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break ;
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}
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add += chain[k][i] ;
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x ++ ;
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p *= len[k] - i ;
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}
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else {
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p *= min ( len[k] + 1 , i + 1 ) ;
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}
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}
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if ( flag ) continue ;
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double fuck = ( add + (x>1?(add*x/cnt):0) ) * p ;
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ans += fuck ;
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}
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}
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printf ( "%.3f\n" , ans / sum ) ;
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}
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return 0 ;
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}
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