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QOJ
| ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
|---|---|---|---|---|---|---|---|---|---|
| #396013 | #5406. 随机游走 | Xun_xiaoyao | 100 ✓ | 639ms | 81964kb | C++14 | 795b | 2024-04-22 09:53:46 | 2024-04-22 09:53:46 |
Judging History
answer
#include <bits/stdc++.h>
#define Mod 1000000007
using namespace std;
inline int qpow(int a,int p)
{
int ret=1;
for(;p;p>>=1,a=1ll*a*a%Mod)
if(p&1) ret=1ll*ret*a%Mod;
return ret;
}
inline void add(int &a,int b){a+=b;if(a>=Mod) a-=Mod;}
inline void del(int &a,int b){a-=b;if(a<0) a+=Mod;}
int fac[10000010],inv[10000010];
inline int C(int n,int m){return (m<0||m>n)?0:1ll*fac[n]*inv[m]%Mod*inv[n-m]%Mod;}
int n,ans,n2,ny;
int main()
{
cin>>n;
n2=n<<1;
fac[0]=inv[0]=1;
for(int i=1;i<=n2;i++) fac[i]=1ll*fac[i-1]*i%Mod;
inv[n2]=qpow(fac[n2],Mod-2);
for(int i=n2-1;i;i--) inv[i]=1ll*inv[i+1]*(i+1)%Mod;
ny=qpow(n2+1,Mod-2);
for(int i=0;i<n;i++)
(i&1?del:add)(ans,1ll*C(n2,i)*inv[n2]%Mod*qpow(n-i,n2+1)%Mod*ny%Mod);
printf("%d\n",2*ans%Mod);
return 0;
}
Details
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Subtask #1:
score: 5
Accepted
Test #1:
score: 5
Accepted
time: 0ms
memory: 5800kb
input:
1
output:
333333336
result:
ok 1 number(s): "333333336"
Test #2:
score: 0
Accepted
time: 0ms
memory: 5896kb
input:
2
output:
266666669
result:
ok 1 number(s): "266666669"
Test #3:
score: 0
Accepted
time: 0ms
memory: 5984kb
input:
3
output:
769047625
result:
ok 1 number(s): "769047625"
Subtask #2:
score: 10
Accepted
Test #4:
score: 10
Accepted
time: 1ms
memory: 5784kb
input:
4
output:
877865968
result:
ok 1 number(s): "877865968"
Test #5:
score: 0
Accepted
time: 0ms
memory: 5852kb
input:
5
output:
733342859
result:
ok 1 number(s): "733342859"
Test #6:
score: 0
Accepted
time: 0ms
memory: 5980kb
input:
6
output:
655899114
result:
ok 1 number(s): "655899114"
Test #7:
score: 0
Accepted
time: 0ms
memory: 5768kb
input:
7
output:
946326757
result:
ok 1 number(s): "946326757"
Test #8:
score: 0
Accepted
time: 1ms
memory: 5920kb
input:
8
output:
230714822
result:
ok 1 number(s): "230714822"
Test #9:
score: 0
Accepted
time: 0ms
memory: 5920kb
input:
9
output:
782967541
result:
ok 1 number(s): "782967541"
Test #10:
score: 0
Accepted
time: 1ms
memory: 5888kb
input:
10
output:
732371611
result:
ok 1 number(s): "732371611"
Subtask #3:
score: 10
Accepted
Test #11:
score: 10
Accepted
time: 1ms
memory: 5848kb
input:
15
output:
677123472
result:
ok 1 number(s): "677123472"
Test #12:
score: 0
Accepted
time: 1ms
memory: 5784kb
input:
13
output:
168974634
result:
ok 1 number(s): "168974634"
Test #13:
score: 0
Accepted
time: 0ms
memory: 5984kb
input:
26
output:
213343876
result:
ok 1 number(s): "213343876"
Test #14:
score: 0
Accepted
time: 1ms
memory: 5800kb
input:
29
output:
631124616
result:
ok 1 number(s): "631124616"
Subtask #4:
score: 15
Accepted
Test #15:
score: 15
Accepted
time: 1ms
memory: 5832kb
input:
37
output:
349256161
result:
ok 1 number(s): "349256161"
Test #16:
score: 0
Accepted
time: 1ms
memory: 5772kb
input:
104
output:
351095881
result:
ok 1 number(s): "351095881"
Test #17:
score: 0
Accepted
time: 1ms
memory: 5912kb
input:
194
output:
895504391
result:
ok 1 number(s): "895504391"
Test #18:
score: 0
Accepted
time: 1ms
memory: 5888kb
input:
197
output:
923555376
result:
ok 1 number(s): "923555376"
Test #19:
score: 0
Accepted
time: 1ms
memory: 5776kb
input:
198
output:
512220517
result:
ok 1 number(s): "512220517"
Subtask #5:
score: 15
Accepted
Test #20:
score: 15
Accepted
time: 1ms
memory: 5888kb
input:
562
output:
255062346
result:
ok 1 number(s): "255062346"
Test #21:
score: 0
Accepted
time: 0ms
memory: 5780kb
input:
1007
output:
735041605
result:
ok 1 number(s): "735041605"
Test #22:
score: 0
Accepted
time: 0ms
memory: 5904kb
input:
1788
output:
208261384
result:
ok 1 number(s): "208261384"
Test #23:
score: 0
Accepted
time: 1ms
memory: 5864kb
input:
1980
output:
875427987
result:
ok 1 number(s): "875427987"
Test #24:
score: 0
Accepted
time: 1ms
memory: 5852kb
input:
1983
output:
571776252
result:
ok 1 number(s): "571776252"
Test #25:
score: 0
Accepted
time: 1ms
memory: 5900kb
input:
1992
output:
12983695
result:
ok 1 number(s): "12983695"
Subtask #6:
score: 15
Accepted
Test #26:
score: 15
Accepted
time: 0ms
memory: 5908kb
input:
3946
output:
977435333
result:
ok 1 number(s): "977435333"
Test #27:
score: 0
Accepted
time: 3ms
memory: 7960kb
input:
65944
output:
312666196
result:
ok 1 number(s): "312666196"
Test #28:
score: 0
Accepted
time: 19ms
memory: 9216kb
input:
163815
output:
163767254
result:
ok 1 number(s): "163767254"
Test #29:
score: 0
Accepted
time: 22ms
memory: 11448kb
input:
198732
output:
911833524
result:
ok 1 number(s): "911833524"
Test #30:
score: 0
Accepted
time: 22ms
memory: 10672kb
input:
199287
output:
910277128
result:
ok 1 number(s): "910277128"
Test #31:
score: 0
Accepted
time: 19ms
memory: 11360kb
input:
199819
output:
561747634
result:
ok 1 number(s): "561747634"
Subtask #7:
score: 30
Accepted
Test #32:
score: 30
Accepted
time: 36ms
memory: 11896kb
input:
315618
output:
602805814
result:
ok 1 number(s): "602805814"
Test #33:
score: 0
Accepted
time: 132ms
memory: 23356kb
input:
1130465
output:
898203793
result:
ok 1 number(s): "898203793"
Test #34:
score: 0
Accepted
time: 552ms
memory: 76624kb
input:
4399723
output:
101317224
result:
ok 1 number(s): "101317224"
Test #35:
score: 0
Accepted
time: 595ms
memory: 80420kb
input:
4804460
output:
114947085
result:
ok 1 number(s): "114947085"
Test #36:
score: 0
Accepted
time: 631ms
memory: 81868kb
input:
4995726
output:
460040939
result:
ok 1 number(s): "460040939"
Test #37:
score: 0
Accepted
time: 639ms
memory: 81864kb
input:
4999919
output:
780785591
result:
ok 1 number(s): "780785591"
Test #38:
score: 0
Accepted
time: 626ms
memory: 81964kb
input:
4999999
output:
742624725
result:
ok 1 number(s): "742624725"