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QOJ
| 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 |
|---|---|---|---|---|---|---|---|---|---|
| #396140 | #5406. 随机游走 | 251Sec | 100 ✓ | 973ms | 160156kb | C++14 | 796b | 2024-04-22 13:42:49 | 2024-04-22 13:42:51 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int P = 1e9 + 7;
int n;
ll fac[10000005], ifac[10000005], ans;
ll QPow(ll a, ll b) {
ll res = 1;
for (; b; b >>= 1) {
if (b & 1) res = res * a % P;
a = a * a % P;
}
return res;
}
ll C(int n, int m) { return fac[n] * ifac[m] % P * ifac[n - m] % P; }
int main() {
scanf("%d", &n);
fac[0] = 1;
for (int i = 1; i <= n * 2; i++) fac[i] = fac[i - 1] * i % P;
ifac[n * 2] = QPow(fac[n * 2], P - 2);
for (int i = n * 2 - 1; ~i; i--) ifac[i] = ifac[i + 1] * (i + 1) % P;
for (int i = 0; i < n; i++) {
ans += C(n * 2, i) * ((i & 1) ? P - 1 : 1) % P * QPow(n - i, 2 * n + 1) % P * QPow(2 * n + 1, P - 2) % P;
}
ans = ans % P * ifac[n * 2] % P * 2 % P;
printf("%lld\n", ans);
return 0;
}
详细
Subtask #1:
score: 5
Accepted
Test #1:
score: 5
Accepted
time: 0ms
memory: 5892kb
input:
1
output:
333333336
result:
ok 1 number(s): "333333336"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5956kb
input:
2
output:
266666669
result:
ok 1 number(s): "266666669"
Test #3:
score: 0
Accepted
time: 1ms
memory: 5976kb
input:
3
output:
769047625
result:
ok 1 number(s): "769047625"
Subtask #2:
score: 10
Accepted
Test #4:
score: 10
Accepted
time: 1ms
memory: 5796kb
input:
4
output:
877865968
result:
ok 1 number(s): "877865968"
Test #5:
score: 0
Accepted
time: 1ms
memory: 5988kb
input:
5
output:
733342859
result:
ok 1 number(s): "733342859"
Test #6:
score: 0
Accepted
time: 1ms
memory: 5988kb
input:
6
output:
655899114
result:
ok 1 number(s): "655899114"
Test #7:
score: 0
Accepted
time: 1ms
memory: 5832kb
input:
7
output:
946326757
result:
ok 1 number(s): "946326757"
Test #8:
score: 0
Accepted
time: 1ms
memory: 5832kb
input:
8
output:
230714822
result:
ok 1 number(s): "230714822"
Test #9:
score: 0
Accepted
time: 1ms
memory: 5848kb
input:
9
output:
782967541
result:
ok 1 number(s): "782967541"
Test #10:
score: 0
Accepted
time: 1ms
memory: 5984kb
input:
10
output:
732371611
result:
ok 1 number(s): "732371611"
Subtask #3:
score: 10
Accepted
Test #11:
score: 10
Accepted
time: 1ms
memory: 5788kb
input:
15
output:
677123472
result:
ok 1 number(s): "677123472"
Test #12:
score: 0
Accepted
time: 1ms
memory: 5900kb
input:
13
output:
168974634
result:
ok 1 number(s): "168974634"
Test #13:
score: 0
Accepted
time: 1ms
memory: 5836kb
input:
26
output:
213343876
result:
ok 1 number(s): "213343876"
Test #14:
score: 0
Accepted
time: 1ms
memory: 5796kb
input:
29
output:
631124616
result:
ok 1 number(s): "631124616"
Subtask #4:
score: 15
Accepted
Test #15:
score: 15
Accepted
time: 1ms
memory: 5984kb
input:
37
output:
349256161
result:
ok 1 number(s): "349256161"
Test #16:
score: 0
Accepted
time: 0ms
memory: 5984kb
input:
104
output:
351095881
result:
ok 1 number(s): "351095881"
Test #17:
score: 0
Accepted
time: 1ms
memory: 5984kb
input:
194
output:
895504391
result:
ok 1 number(s): "895504391"
Test #18:
score: 0
Accepted
time: 1ms
memory: 5836kb
input:
197
output:
923555376
result:
ok 1 number(s): "923555376"
Test #19:
score: 0
Accepted
time: 1ms
memory: 5980kb
input:
198
output:
512220517
result:
ok 1 number(s): "512220517"
Subtask #5:
score: 15
Accepted
Test #20:
score: 15
Accepted
time: 1ms
memory: 5944kb
input:
562
output:
255062346
result:
ok 1 number(s): "255062346"
Test #21:
score: 0
Accepted
time: 1ms
memory: 5848kb
input:
1007
output:
735041605
result:
ok 1 number(s): "735041605"
Test #22:
score: 0
Accepted
time: 1ms
memory: 5864kb
input:
1788
output:
208261384
result:
ok 1 number(s): "208261384"
Test #23:
score: 0
Accepted
time: 1ms
memory: 5984kb
input:
1980
output:
875427987
result:
ok 1 number(s): "875427987"
Test #24:
score: 0
Accepted
time: 1ms
memory: 5876kb
input:
1983
output:
571776252
result:
ok 1 number(s): "571776252"
Test #25:
score: 0
Accepted
time: 1ms
memory: 5860kb
input:
1992
output:
12983695
result:
ok 1 number(s): "12983695"
Subtask #6:
score: 15
Accepted
Test #26:
score: 15
Accepted
time: 1ms
memory: 6016kb
input:
3946
output:
977435333
result:
ok 1 number(s): "977435333"
Test #27:
score: 0
Accepted
time: 11ms
memory: 6876kb
input:
65944
output:
312666196
result:
ok 1 number(s): "312666196"
Test #28:
score: 0
Accepted
time: 31ms
memory: 11488kb
input:
163815
output:
163767254
result:
ok 1 number(s): "163767254"
Test #29:
score: 0
Accepted
time: 32ms
memory: 13376kb
input:
198732
output:
911833524
result:
ok 1 number(s): "911833524"
Test #30:
score: 0
Accepted
time: 32ms
memory: 12224kb
input:
199287
output:
910277128
result:
ok 1 number(s): "910277128"
Test #31:
score: 0
Accepted
time: 32ms
memory: 11632kb
input:
199819
output:
561747634
result:
ok 1 number(s): "561747634"
Subtask #7:
score: 30
Accepted
Test #32:
score: 30
Accepted
time: 54ms
memory: 16108kb
input:
315618
output:
602805814
result:
ok 1 number(s): "602805814"
Test #33:
score: 0
Accepted
time: 213ms
memory: 43980kb
input:
1130465
output:
898203793
result:
ok 1 number(s): "898203793"
Test #34:
score: 0
Accepted
time: 832ms
memory: 142416kb
input:
4399723
output:
101317224
result:
ok 1 number(s): "101317224"
Test #35:
score: 0
Accepted
time: 929ms
memory: 155140kb
input:
4804460
output:
114947085
result:
ok 1 number(s): "114947085"
Test #36:
score: 0
Accepted
time: 968ms
memory: 159964kb
input:
4995726
output:
460040939
result:
ok 1 number(s): "460040939"
Test #37:
score: 0
Accepted
time: 970ms
memory: 160092kb
input:
4999919
output:
780785591
result:
ok 1 number(s): "780785591"
Test #38:
score: 0
Accepted
time: 973ms
memory: 160156kb
input:
4999999
output:
742624725
result:
ok 1 number(s): "742624725"