oj.uz

Submission #20025

# Submission time Handle Problem Language Result Execution time Memory
20025 2016-02-25T08:41:27 Z Namnamseo 카드 (kriii4_Z) C++14
0 / 100
 8 ms 87868 KB 
#include<cstdio>
#include<cstring>
long long a,b,i,c,aa,bb=1,x,X=1e9+7,D[3333][3333];
long long pow(long long aa,long long bb){
    if(bb==0) return 1;
    long long ret=pow(aa,bb/2);
    ret=(ret*ret)%X;
    if(bb&1) ret=(ret*aa)%X;
    return ret;
}
long long f(long long C,long long L)
{
    if(D[C][L]>=0)return D[C][L];
    if(L==0)return D[C][L]=0;
    if(C>L)return D[C][L]=0;
    if(C==1&&L==1)return D[C][L]=1;
    return D[C][L]=(C*f(C-1,L-1)%X+(a-C)*f(C,L-1)%X)%X;
}
main()
{
    memset(D,-1,sizeof(D));
    scanf("%lld%lld",&a,&b);
    for(i=1;i<=a;i++){scanf("%lld",&x);if(x==1)c++;};
    aa=f(c,b);
    for(i=1;i<=a;i++)bb*=a,bb%=X;
    printf("%lld",aa*pow(bb,X-2)%X);
}

Subtask #1
0.0 / 13.0

# Verdict Execution time Memory Grader output
1 Runtime error 8 ms 87868 KB SIGSEGV Segmentation fault
2 Halted 0 ms 0 KB -

Subtask #2
0.0 / 87.0

# Verdict Execution time Memory Grader output
1 Halted 0 ms 0 KB -