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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
#82344#5406. 随机游走zhouhuanyi0 239ms238116kbC++231.2kb2023-02-27 16:20:362023-02-27 16:20:37

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.
  • [2023-02-27 16:20:37]
  • 评测
  • 测评结果:0
  • 用时:239ms
  • 内存:238116kb
  • [2023-02-27 16:20:36]
  • 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 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;
}
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],inv[N+1];
int C(int x,int y)
{
    if (x<y) return 0;
    return 1ll*fac[x]*invfac[y]%mod*invfac[x-y]%mod;
}
int main()
{
    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;
    for (int i=1;i<=N;++i) inv[i]=1ll*fac[i-1]*invfac[i]%mod;
    n=read(),ans=1;
    for (int i=0;i<=n;++i)
    {
	if (!(i&1)) Adder2(ans,-1ll*C(n,i)*inv[(i<<1)+1]%mod);
	else Adder(ans,1ll*C(n,i)*inv[(i<<1)+1]%mod);
    }
    printf("%d\n",ans);
    return 0;
}

详细

Subtask #1:

score: 0
Wrong Answer

Test #1:

score: 5
Accepted
time: 209ms
memory: 237888kb

input:

1

output:

333333336

result:

ok 1 number(s): "333333336"

Test #2:

score: 0
Accepted
time: 233ms
memory: 237844kb

input:

2

output:

266666669

result:

ok 1 number(s): "266666669"

Test #3:

score: -5
Wrong Answer
time: 214ms
memory: 238112kb

input:

3

output:

942857150

result:

wrong answer 1st numbers differ - expected: '769047625', found: '942857150'

Subtask #2:

score: 0
Wrong Answer

Test #4:

score: 0
Wrong Answer
time: 233ms
memory: 237908kb

input:

4

output:

393650797

result:

wrong answer 1st numbers differ - expected: '877865968', found: '393650797'

Subtask #3:

score: 0
Wrong Answer

Test #11:

score: 0
Wrong Answer
time: 236ms
memory: 237844kb

input:

15

output:

571674925

result:

wrong answer 1st numbers differ - expected: '677123472', found: '571674925'

Subtask #4:

score: 0
Wrong Answer

Test #15:

score: 0
Wrong Answer
time: 239ms
memory: 238116kb

input:

37

output:

917610801

result:

wrong answer 1st numbers differ - expected: '349256161', found: '917610801'

Subtask #5:

score: 0
Wrong Answer

Test #20:

score: 0
Wrong Answer
time: 193ms
memory: 237900kb

input:

562

output:

993027929

result:

wrong answer 1st numbers differ - expected: '255062346', found: '993027929'

Subtask #6:

score: 0
Wrong Answer

Test #26:

score: 0
Wrong Answer
time: 212ms
memory: 237900kb

input:

3946

output:

692327942

result:

wrong answer 1st numbers differ - expected: '977435333', found: '692327942'

Subtask #7:

score: 0
Wrong Answer

Test #32:

score: 0
Wrong Answer
time: 221ms
memory: 238032kb

input:

315618

output:

2044765

result:

wrong answer 1st numbers differ - expected: '602805814', found: '2044765'