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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#228996#6137. Sub-cycle GraphISYRHHWA 83ms5236kbC++141.1kb2023-10-28 14:45:032023-10-28 14:45:45

Judging History

你现在查看的是最新测评结果

  • [2023-10-28 14:45:45]
  • 评测
  • 测评结果:WA
  • 用时:83ms
  • 内存:5236kb
  • [2023-10-28 14:45:03]
  • 提交

answer

#include<bits/stdc++.h>
#define FOR(i,a,b) for(int i=a,i##i=b;i<=i##i;++i)
#define ROF(i,a,b) for(int i=a,i##i=b;i>=i##i;--i)
using namespace std;
typedef long long ll;
const int N=1e5+7,mod=1e9+7,i2=(mod+1)/2;
ll n,fac[N],ifac[N],m;
inline ll qpow(ll a,ll b){
    ll R=1;a%=mod;
    for(;b;b>>=1,a=a*a%mod)if(b&1)R=R*a%mod;
    return R;
}
inline ll C(int n,int m){
    return fac[n]*1ll*ifac[m]%mod*ifac[n-m]%mod;
}
void work(){
    scanf("%lld%lld",&n,&m);
    if(m>n){
        puts("0");
        return;
    }
    if(m==n){
        puts("1");
        return;
    }
    ll ans=0,s2=1;
    FOR(i,0,min(m,n-m)){
        ans+=(i&1?mod-1ll:1ll)*s2%mod*C(n-m,i)%mod*C(n-i-1,m-i)%mod;
        if(ans>=mod)ans-=mod;
        s2=s2*i2%mod;
    }
    ans%=mod;
    ans=ans*fac[n]%mod*ifac[n-m]%mod;
    printf("%lld\n",(ans+mod)%mod);
}
signed main(){
//    freopen("dt.in","r",stdin);
    int T;
    scanf("%d",&T);
    *fac=1;
    FOR(i,1,N-1)fac[i]=fac[i-1]*1ll*i%mod;
    ifac[N-1]=qpow(fac[N-1],mod-2);
    ROF(i,N-2,0)ifac[i]=(i+1ll)*ifac[i+1]%mod;
    while(T--)work();
    return 0;
}

詳細信息

Test #1:

score: 100
Accepted
time: 2ms
memory: 5200kb

input:

3
4 2
4 3
5 3

output:

15
12
90

result:

ok 3 number(s): "15 12 90"

Test #2:

score: -100
Wrong Answer
time: 83ms
memory: 5236kb

input:

17446
3 0
3 1
3 2
3 3
4 0
4 1
4 2
4 3
4 4
5 0
5 1
5 2
5 3
5 4
5 5
6 0
6 1
6 2
6 3
6 4
6 5
6 6
7 0
7 1
7 2
7 3
7 4
7 5
7 6
7 7
8 0
8 1
8 2
8 3
8 4
8 5
8 6
8 7
8 8
9 0
9 1
9 2
9 3
9 4
9 5
9 6
9 7
9 8
9 9
10 0
10 1
10 2
10 3
10 4
10 5
10 6
10 7
10 8
10 9
10 10
11 0
11 1
11 2
11 3
11 4
11 5
11 6
11 7
11...

output:

1
3
3
1
1
6
15
12
1
1
10
45
90
60
1
1
15
105
375
630
360
1
1
21
210
1155
3465
5040
2520
1
1
28
378
2940
13545
35280
45360
20160
1
1
36
630
6552
42525
170100
393120
453600
181440
1
1
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
1
1
55
1485
24750
273735
2047815
10239075
32848200
62370000...

result:

wrong answer 9th numbers differ - expected: '3', found: '1'