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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#396167 | #5406. 随机游走 | jiajia | 100 ✓ | 493ms | 160248kb | C++20 | 958b | 2024-04-22 14:16:33 | 2024-04-22 14:16:33 |
Judging History
answer
#include <bits/stdc++.h>
#define LL long long
using namespace std;
const int NR = 1e7 + 5, MOD = 1e9 + 7;
LL qpow(LL x, LL y) {
LL res = 1;
while (y) {
if (y & 1) res = res * x % MOD;
y >>= 1, x = x * x % MOD;
}
return res;
}
int n, tn;
LL fac[NR], ifac[NR];
LL C(int x, int y) {
return fac[x] * ifac[y] % MOD * ifac[x - y] % MOD;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n, tn = n << 1;
fac[0] = 1;
for (int i = 1; i <= tn; i++) fac[i] = fac[i - 1] * i % MOD;
ifac[tn] = qpow(fac[tn], MOD - 2);
for (int i = tn; i >= 1; i--) ifac[i - 1] = ifac[i] * i % MOD;
LL ans = 0;
for (int i = 0; i < n; i++)
(ans += (i & 1 ? MOD - 1 : 1) * C(tn, i) % MOD * qpow(n - i, tn + 1)) %= MOD;
cout << ans * ifac[tn] % MOD * qpow(tn + 1, MOD - 2) % MOD * 2 % MOD << '\n';
cerr << (double)clock() / CLOCKS_PER_SEC << endl;
return 0;
}
Details
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Subtask #1:
score: 5
Accepted
Test #1:
score: 5
Accepted
time: 1ms
memory: 6096kb
input:
1
output:
333333336
result:
ok 1 number(s): "333333336"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5912kb
input:
2
output:
266666669
result:
ok 1 number(s): "266666669"
Test #3:
score: 0
Accepted
time: 1ms
memory: 5988kb
input:
3
output:
769047625
result:
ok 1 number(s): "769047625"
Subtask #2:
score: 10
Accepted
Test #4:
score: 10
Accepted
time: 1ms
memory: 6044kb
input:
4
output:
877865968
result:
ok 1 number(s): "877865968"
Test #5:
score: 0
Accepted
time: 1ms
memory: 6044kb
input:
5
output:
733342859
result:
ok 1 number(s): "733342859"
Test #6:
score: 0
Accepted
time: 1ms
memory: 6040kb
input:
6
output:
655899114
result:
ok 1 number(s): "655899114"
Test #7:
score: 0
Accepted
time: 1ms
memory: 6040kb
input:
7
output:
946326757
result:
ok 1 number(s): "946326757"
Test #8:
score: 0
Accepted
time: 1ms
memory: 6044kb
input:
8
output:
230714822
result:
ok 1 number(s): "230714822"
Test #9:
score: 0
Accepted
time: 1ms
memory: 6040kb
input:
9
output:
782967541
result:
ok 1 number(s): "782967541"
Test #10:
score: 0
Accepted
time: 1ms
memory: 6092kb
input:
10
output:
732371611
result:
ok 1 number(s): "732371611"
Subtask #3:
score: 10
Accepted
Test #11:
score: 10
Accepted
time: 1ms
memory: 5984kb
input:
15
output:
677123472
result:
ok 1 number(s): "677123472"
Test #12:
score: 0
Accepted
time: 1ms
memory: 6048kb
input:
13
output:
168974634
result:
ok 1 number(s): "168974634"
Test #13:
score: 0
Accepted
time: 1ms
memory: 6032kb
input:
26
output:
213343876
result:
ok 1 number(s): "213343876"
Test #14:
score: 0
Accepted
time: 1ms
memory: 6036kb
input:
29
output:
631124616
result:
ok 1 number(s): "631124616"
Subtask #4:
score: 15
Accepted
Test #15:
score: 15
Accepted
time: 1ms
memory: 6096kb
input:
37
output:
349256161
result:
ok 1 number(s): "349256161"
Test #16:
score: 0
Accepted
time: 1ms
memory: 6044kb
input:
104
output:
351095881
result:
ok 1 number(s): "351095881"
Test #17:
score: 0
Accepted
time: 1ms
memory: 6028kb
input:
194
output:
895504391
result:
ok 1 number(s): "895504391"
Test #18:
score: 0
Accepted
time: 1ms
memory: 5988kb
input:
197
output:
923555376
result:
ok 1 number(s): "923555376"
Test #19:
score: 0
Accepted
time: 1ms
memory: 6044kb
input:
198
output:
512220517
result:
ok 1 number(s): "512220517"
Subtask #5:
score: 15
Accepted
Test #20:
score: 15
Accepted
time: 0ms
memory: 6052kb
input:
562
output:
255062346
result:
ok 1 number(s): "255062346"
Test #21:
score: 0
Accepted
time: 1ms
memory: 6056kb
input:
1007
output:
735041605
result:
ok 1 number(s): "735041605"
Test #22:
score: 0
Accepted
time: 1ms
memory: 6080kb
input:
1788
output:
208261384
result:
ok 1 number(s): "208261384"
Test #23:
score: 0
Accepted
time: 1ms
memory: 6128kb
input:
1980
output:
875427987
result:
ok 1 number(s): "875427987"
Test #24:
score: 0
Accepted
time: 0ms
memory: 5936kb
input:
1983
output:
571776252
result:
ok 1 number(s): "571776252"
Test #25:
score: 0
Accepted
time: 0ms
memory: 6032kb
input:
1992
output:
12983695
result:
ok 1 number(s): "12983695"
Subtask #6:
score: 15
Accepted
Test #26:
score: 15
Accepted
time: 1ms
memory: 6060kb
input:
3946
output:
977435333
result:
ok 1 number(s): "977435333"
Test #27:
score: 0
Accepted
time: 5ms
memory: 6944kb
input:
65944
output:
312666196
result:
ok 1 number(s): "312666196"
Test #28:
score: 0
Accepted
time: 11ms
memory: 11748kb
input:
163815
output:
163767254
result:
ok 1 number(s): "163767254"
Test #29:
score: 0
Accepted
time: 17ms
memory: 14696kb
input:
198732
output:
911833524
result:
ok 1 number(s): "911833524"
Test #30:
score: 0
Accepted
time: 17ms
memory: 12236kb
input:
199287
output:
910277128
result:
ok 1 number(s): "910277128"
Test #31:
score: 0
Accepted
time: 17ms
memory: 13368kb
input:
199819
output:
561747634
result:
ok 1 number(s): "561747634"
Subtask #7:
score: 30
Accepted
Test #32:
score: 30
Accepted
time: 24ms
memory: 16036kb
input:
315618
output:
602805814
result:
ok 1 number(s): "602805814"
Test #33:
score: 0
Accepted
time: 106ms
memory: 42196kb
input:
1130465
output:
898203793
result:
ok 1 number(s): "898203793"
Test #34:
score: 0
Accepted
time: 418ms
memory: 142872kb
input:
4399723
output:
101317224
result:
ok 1 number(s): "101317224"
Test #35:
score: 0
Accepted
time: 455ms
memory: 155068kb
input:
4804460
output:
114947085
result:
ok 1 number(s): "114947085"
Test #36:
score: 0
Accepted
time: 488ms
memory: 159988kb
input:
4995726
output:
460040939
result:
ok 1 number(s): "460040939"
Test #37:
score: 0
Accepted
time: 493ms
memory: 160052kb
input:
4999919
output:
780785591
result:
ok 1 number(s): "780785591"
Test #38:
score: 0
Accepted
time: 489ms
memory: 160248kb
input:
4999999
output:
742624725
result:
ok 1 number(s): "742624725"