Submission #20009

#	Time	Username	Problem	Language	Result	Execution time	Memory
20009		ainta	악수 (kriii4_D)	C++98	5 / 100	4000 ms	1084 KiB

D

#include<stdio.h>
int n, F[11], cnt;
long long Mod = 1000000007, Res;
bool E[11][11], v[11];
long long Pow(long long a, int b){
    long long r = 1;
    while(b){
        if(b&1)r=r*a%Mod;
        a=a*a%Mod;
        b>>=1;
    }
    return r;
}
void DFS(int a){
    cnt++;
    v[a]=true;
    int i;
    for(i=1;i<=n;i++)if(!v[i]&&E[a][i])DFS(i);
}
void Do(int cc){
    int i,j;
    cnt = 0;
    for(i=1;i<=n;i++)v[i]=false;
    DFS(1);
    if(cnt == n){
        Res = (Res + cc*Pow(F[n*(n-1)/2]/F[n*(n-1)/2-cc],Mod-2))%Mod;
        return;
    }
    for(i=1;i<n;i++){
        for(j=i+1;j<=n;j++){
            if(!E[i][j]){
                E[i][j]=E[j][i]=1;
                Do(cc+1);
                E[i][j]=E[j][i]=0;
            }
        }
    }
}
int main(){
    int i;
    F[0]=1;
    for(i=1;i<=10;i++)F[i]=F[i-1]*i;
    scanf("%d",&n);
    Do(0);
    printf("%lld\n",Res);
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 95