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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
#91058#6137. Sub-cycle GraphyyyyxhWA 145ms9260kbC++171.2kb2023-03-26 22:19:112023-03-26 22:19:13

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-03-26 22:19:13]
  • 评测
  • 测评结果:WA
  • 用时:145ms
  • 内存:9260kb
  • [2023-03-26 22:19:11]
  • 提交

answer

#include <cstdio>
using namespace std;
template<typename T>
T read(){
	char c=getchar();T x=0;
	while(c<48||c>57) c=getchar();
	do x=(x<<1)+(x<<3)+(c^48),c=getchar();
	while(c>=48&&c<=57);
	return x;
}
typedef long long ll;
const int P=1000000007;
int qp(int a,int b=P-2){
	int res=1;
	while(b){
		if(b&1) res=(ll)res*a%P;
		a=(ll)a*a%P;b>>=1;
	}
	return res;
}
int fac[1000003],fiv[1000003];
int comb(int a,int b){
	if(b<0||b>a) return 0;
	return (ll)fac[a]*fiv[b]%P*fiv[a-b]%P;
}
void inc(int &x,int v){if((x+=v)>=P) x-=P;}
void dec(int &x,int v){if((x-=v)<0) x+=P;}
int main(){
	int tc=read<int>();
	fac[0]=1;
	for(int i=1;i<=1000000;++i) fac[i]=(ll)fac[i-1]*i%P;
	fiv[1000000]=qp(fac[1000000]);
	for(int i=1000000;i;--i) fiv[i-1]=(ll)fiv[i]*i%P;
	while(tc--){
		int n=read<int>();
		ll m=read<ll>();
		if(m>n){puts("0");continue;}
		if(m==n){printf("%d\n",fac[n-1]);continue;}
		m=n-m;
		int pw=1,res=0;
		for(int i=0;i<=m;++i){
			if((m^i)&1) dec(res,(ll)comb(m,i)*pw%P*comb(n-m+i-1,m-1)%P);
			else inc(res,(ll)comb(m,i)*pw%P*comb(n-m+i-1,m-1)%P);
			inc(pw,pw);
		}
		res=(ll)res*fiv[m]%P*fac[n]%P*qp((P+1)>>1,m)%P;
		printf("%d\n",res);
	}
	return 0;
}

詳細信息

Test #1:

score: 100
Accepted
time: 0ms
memory: 9260kb

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: 145ms
memory: 9240kb

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
2
1
6
15
12
6
1
10
45
90
60
24
1
15
105
375
630
360
120
1
21
210
1155
3465
5040
2520
720
1
28
378
2940
13545
35280
45360
20160
5040
1
36
630
6552
42525
170100
393120
453600
181440
40320
1
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
362880
1
55
1485
24750
273735
2047815
10239075
...

result:

wrong answer 4th numbers differ - expected: '1', found: '2'