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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
#227112#5406. 随机游走zhouhuanyi70 837ms160072kbC++231.4kb2023-10-26 22:35:032023-10-26 22:35:03

Judging History

你现在查看的是最新测评结果

  • [2023-10-26 22:35:03]
  • 评测
  • 测评结果:70
  • 用时:837ms
  • 内存:160072kb
  • [2023-10-26 22:35:03]
  • 提交

answer

#include<iostream>
#include<cstdio>
#define N 20000000
#define mod 1000000007
using namespace std;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
int MD(int x)
{
	return x>=mod?x-mod:x;
}
int MD2(int x)
{
	return x<0?x+mod:x;
}
void Adder(int &x,int d)
{
	x+=d;
	if (x>=mod) x-=mod;
	return;
}
void Adder2(int &x,int d)
{
	x+=d;
	if (x<0) x+=mod;
	return;
}
int n,ans,fac[N+1],invfac[N+1];
int fast_pow(int a,int b)
{
	int res=1,mul=a;
	while (b)
	{
		if (b&1) res=1ll*res*mul%mod;
		mul=1ll*mul*mul%mod,b>>=1;
	}
	return res;
}
int C(int x,int y)
{
	if (x<y) return 0;
	return 1ll*fac[x]*invfac[y]%mod*invfac[x-y]%mod;
}
int calc(int x)
{
	return 1ll*fast_pow(x,n<<1)*invfac[n<<1]%mod;
}
int calc2(int x)
{
	return 1ll*fast_pow(x,(n<<1)+1)*MD2(invfac[n<<1]-invfac[(n<<1)+1])%mod;
}
int main()
{
	int l;
	fac[0]=1;
	for (int i=1;i<=N;++i) fac[i]=1ll*fac[i-1]*i%mod;
	invfac[N]=fast_pow(fac[N],mod-2);
	for (int i=N-1;i>=0;--i) invfac[i]=1ll*invfac[i+1]*(i+1)%mod;
	n=read();
	for (int i=0;i<=(n<<1);++i)
	{
		l=max(n-i,0);
		if (!(i&1)) Adder(ans,1ll*C(n<<1,i)*MD2(MD2(calc2((n<<1)-i)-calc2(l))-1ll*MD2(calc((n<<1)-i)-calc(l))*MD2(n-i)%mod)%mod);
		else Adder2(ans,-1ll*C(n<<1,i)*MD2(MD2(calc2((n<<1)-i)-calc2(l))-1ll*MD2(calc((n<<1)-i)-calc(l))*MD2(n-i)%mod)%mod);
	}
	printf("%lld\n",2ll*ans%mod);
	return 0;
}

详细

Subtask #1:

score: 5
Accepted

Test #1:

score: 5
Accepted
time: 160ms
memory: 159780kb

input:

1

output:

333333336

result:

ok 1 number(s): "333333336"

Test #2:

score: 0
Accepted
time: 192ms
memory: 159788kb

input:

2

output:

266666669

result:

ok 1 number(s): "266666669"

Test #3:

score: 0
Accepted
time: 150ms
memory: 160020kb

input:

3

output:

769047625

result:

ok 1 number(s): "769047625"

Subtask #2:

score: 10
Accepted

Test #4:

score: 10
Accepted
time: 139ms
memory: 159972kb

input:

4

output:

877865968

result:

ok 1 number(s): "877865968"

Test #5:

score: 0
Accepted
time: 153ms
memory: 159844kb

input:

5

output:

733342859

result:

ok 1 number(s): "733342859"

Test #6:

score: 0
Accepted
time: 205ms
memory: 159840kb

input:

6

output:

655899114

result:

ok 1 number(s): "655899114"

Test #7:

score: 0
Accepted
time: 175ms
memory: 160004kb

input:

7

output:

946326757

result:

ok 1 number(s): "946326757"

Test #8:

score: 0
Accepted
time: 187ms
memory: 159844kb

input:

8

output:

230714822

result:

ok 1 number(s): "230714822"

Test #9:

score: 0
Accepted
time: 143ms
memory: 160072kb

input:

9

output:

782967541

result:

ok 1 number(s): "782967541"

Test #10:

score: 0
Accepted
time: 163ms
memory: 159744kb

input:

10

output:

732371611

result:

ok 1 number(s): "732371611"

Subtask #3:

score: 10
Accepted

Test #11:

score: 10
Accepted
time: 174ms
memory: 160000kb

input:

15

output:

677123472

result:

ok 1 number(s): "677123472"

Test #12:

score: 0
Accepted
time: 195ms
memory: 159864kb

input:

13

output:

168974634

result:

ok 1 number(s): "168974634"

Test #13:

score: 0
Accepted
time: 172ms
memory: 159836kb

input:

26

output:

213343876

result:

ok 1 number(s): "213343876"

Test #14:

score: 0
Accepted
time: 191ms
memory: 159716kb

input:

29

output:

631124616

result:

ok 1 number(s): "631124616"

Subtask #4:

score: 15
Accepted

Test #15:

score: 15
Accepted
time: 171ms
memory: 159840kb

input:

37

output:

349256161

result:

ok 1 number(s): "349256161"

Test #16:

score: 0
Accepted
time: 167ms
memory: 159964kb

input:

104

output:

351095881

result:

ok 1 number(s): "351095881"

Test #17:

score: 0
Accepted
time: 167ms
memory: 159716kb

input:

194

output:

895504391

result:

ok 1 number(s): "895504391"

Test #18:

score: 0
Accepted
time: 189ms
memory: 159840kb

input:

197

output:

923555376

result:

ok 1 number(s): "923555376"

Test #19:

score: 0
Accepted
time: 187ms
memory: 159712kb

input:

198

output:

512220517

result:

ok 1 number(s): "512220517"

Subtask #5:

score: 15
Accepted

Test #20:

score: 15
Accepted
time: 163ms
memory: 159844kb

input:

562

output:

255062346

result:

ok 1 number(s): "255062346"

Test #21:

score: 0
Accepted
time: 192ms
memory: 159792kb

input:

1007

output:

735041605

result:

ok 1 number(s): "735041605"

Test #22:

score: 0
Accepted
time: 184ms
memory: 160072kb

input:

1788

output:

208261384

result:

ok 1 number(s): "208261384"

Test #23:

score: 0
Accepted
time: 179ms
memory: 159712kb

input:

1980

output:

875427987

result:

ok 1 number(s): "875427987"

Test #24:

score: 0
Accepted
time: 184ms
memory: 159792kb

input:

1983

output:

571776252

result:

ok 1 number(s): "571776252"

Test #25:

score: 0
Accepted
time: 183ms
memory: 159716kb

input:

1992

output:

12983695

result:

ok 1 number(s): "12983695"

Subtask #6:

score: 15
Accepted

Test #26:

score: 15
Accepted
time: 181ms
memory: 159780kb

input:

3946

output:

977435333

result:

ok 1 number(s): "977435333"

Test #27:

score: 0
Accepted
time: 223ms
memory: 159964kb

input:

65944

output:

312666196

result:

ok 1 number(s): "312666196"

Test #28:

score: 0
Accepted
time: 271ms
memory: 159972kb

input:

163815

output:

163767254

result:

ok 1 number(s): "163767254"

Test #29:

score: 0
Accepted
time: 258ms
memory: 159784kb

input:

198732

output:

911833524

result:

ok 1 number(s): "911833524"

Test #30:

score: 0
Accepted
time: 261ms
memory: 160024kb

input:

199287

output:

910277128

result:

ok 1 number(s): "910277128"

Test #31:

score: 0
Accepted
time: 284ms
memory: 159716kb

input:

199819

output:

561747634

result:

ok 1 number(s): "561747634"

Subtask #7:

score: 0
Time Limit Exceeded

Test #32:

score: 30
Accepted
time: 293ms
memory: 159836kb

input:

315618

output:

602805814

result:

ok 1 number(s): "602805814"

Test #33:

score: 0
Accepted
time: 837ms
memory: 159784kb

input:

1130465

output:

898203793

result:

ok 1 number(s): "898203793"

Test #34:

score: -30
Time Limit Exceeded

input:

4399723

output:


result: