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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 |
|---|---|---|---|---|---|---|---|---|---|
| #373876 | #5406. 随机游走 | zhaohaikun | 100 ✓ | 559ms | 120892kb | C++14 | 902b | 2024-04-02 09:46:15 | 2024-04-02 09:46:16 |
Judging History
answer
#include <bits/stdc++.h>
#define F(i, x, y) for (int i = (x); i <= (y); i++)
using namespace std;
typedef long long ll;
const int N = 1e7 + 10, MOD = 1e9 + 7;
int n, ans, fac[N], ifac[N], inv[N];
inline void binom(int x) {
fac[0] = ifac[0] = inv[1] = 1;
F(i, 2, x) inv[i] = (ll) (MOD - MOD / i) * inv[MOD % i] % MOD;
F(i, 1, x) fac[i] = (ll) fac[i - 1] * i % MOD, ifac[i] = (ll) ifac[i - 1] * inv[i] % MOD;
}
inline int C(int x, int y) {return x < y || y < 0 ? 0 : (ll) fac[x] * ifac[y] % MOD * ifac[x - y] % MOD;}
inline int power(int x, int y = MOD - 2) {
int ans = 1;
for (; y; x = (ll) x * x % MOD, y >>= 1)
if (y & 1) ans = (ll) ans * x % MOD;
return ans;
}
signed main() {
binom(N - 1);
cin >> n;
F(i, 0, n) ans = (ans + 2ll * ifac[2 * n + 1] % MOD * power(n - i, 2 * n + 1) % MOD * C(2 * n, i) % MOD * ((i & 1) ? MOD - 1 : 1)) % MOD;
cout << ans;
return 0;
}
详细
Subtask #1:
score: 5
Accepted
Test #1:
score: 5
Accepted
time: 113ms
memory: 120844kb
input:
1
output:
333333336
result:
ok 1 number(s): "333333336"
Test #2:
score: 0
Accepted
time: 94ms
memory: 120668kb
input:
2
output:
266666669
result:
ok 1 number(s): "266666669"
Test #3:
score: 0
Accepted
time: 90ms
memory: 120720kb
input:
3
output:
769047625
result:
ok 1 number(s): "769047625"
Subtask #2:
score: 10
Accepted
Test #4:
score: 10
Accepted
time: 91ms
memory: 120868kb
input:
4
output:
877865968
result:
ok 1 number(s): "877865968"
Test #5:
score: 0
Accepted
time: 98ms
memory: 120772kb
input:
5
output:
733342859
result:
ok 1 number(s): "733342859"
Test #6:
score: 0
Accepted
time: 99ms
memory: 120668kb
input:
6
output:
655899114
result:
ok 1 number(s): "655899114"
Test #7:
score: 0
Accepted
time: 92ms
memory: 120720kb
input:
7
output:
946326757
result:
ok 1 number(s): "946326757"
Test #8:
score: 0
Accepted
time: 100ms
memory: 120676kb
input:
8
output:
230714822
result:
ok 1 number(s): "230714822"
Test #9:
score: 0
Accepted
time: 106ms
memory: 120716kb
input:
9
output:
782967541
result:
ok 1 number(s): "782967541"
Test #10:
score: 0
Accepted
time: 96ms
memory: 120780kb
input:
10
output:
732371611
result:
ok 1 number(s): "732371611"
Subtask #3:
score: 10
Accepted
Test #11:
score: 10
Accepted
time: 99ms
memory: 120792kb
input:
15
output:
677123472
result:
ok 1 number(s): "677123472"
Test #12:
score: 0
Accepted
time: 93ms
memory: 120776kb
input:
13
output:
168974634
result:
ok 1 number(s): "168974634"
Test #13:
score: 0
Accepted
time: 98ms
memory: 120668kb
input:
26
output:
213343876
result:
ok 1 number(s): "213343876"
Test #14:
score: 0
Accepted
time: 104ms
memory: 120892kb
input:
29
output:
631124616
result:
ok 1 number(s): "631124616"
Subtask #4:
score: 15
Accepted
Test #15:
score: 15
Accepted
time: 100ms
memory: 120776kb
input:
37
output:
349256161
result:
ok 1 number(s): "349256161"
Test #16:
score: 0
Accepted
time: 118ms
memory: 120780kb
input:
104
output:
351095881
result:
ok 1 number(s): "351095881"
Test #17:
score: 0
Accepted
time: 88ms
memory: 120768kb
input:
194
output:
895504391
result:
ok 1 number(s): "895504391"
Test #18:
score: 0
Accepted
time: 99ms
memory: 120844kb
input:
197
output:
923555376
result:
ok 1 number(s): "923555376"
Test #19:
score: 0
Accepted
time: 110ms
memory: 120792kb
input:
198
output:
512220517
result:
ok 1 number(s): "512220517"
Subtask #5:
score: 15
Accepted
Test #20:
score: 15
Accepted
time: 94ms
memory: 120664kb
input:
562
output:
255062346
result:
ok 1 number(s): "255062346"
Test #21:
score: 0
Accepted
time: 114ms
memory: 120872kb
input:
1007
output:
735041605
result:
ok 1 number(s): "735041605"
Test #22:
score: 0
Accepted
time: 95ms
memory: 120876kb
input:
1788
output:
208261384
result:
ok 1 number(s): "208261384"
Test #23:
score: 0
Accepted
time: 101ms
memory: 120772kb
input:
1980
output:
875427987
result:
ok 1 number(s): "875427987"
Test #24:
score: 0
Accepted
time: 95ms
memory: 120672kb
input:
1983
output:
571776252
result:
ok 1 number(s): "571776252"
Test #25:
score: 0
Accepted
time: 96ms
memory: 120840kb
input:
1992
output:
12983695
result:
ok 1 number(s): "12983695"
Subtask #6:
score: 15
Accepted
Test #26:
score: 15
Accepted
time: 87ms
memory: 120820kb
input:
3946
output:
977435333
result:
ok 1 number(s): "977435333"
Test #27:
score: 0
Accepted
time: 103ms
memory: 120716kb
input:
65944
output:
312666196
result:
ok 1 number(s): "312666196"
Test #28:
score: 0
Accepted
time: 104ms
memory: 120672kb
input:
163815
output:
163767254
result:
ok 1 number(s): "163767254"
Test #29:
score: 0
Accepted
time: 99ms
memory: 120848kb
input:
198732
output:
911833524
result:
ok 1 number(s): "911833524"
Test #30:
score: 0
Accepted
time: 118ms
memory: 120820kb
input:
199287
output:
910277128
result:
ok 1 number(s): "910277128"
Test #31:
score: 0
Accepted
time: 114ms
memory: 120788kb
input:
199819
output:
561747634
result:
ok 1 number(s): "561747634"
Subtask #7:
score: 30
Accepted
Test #32:
score: 30
Accepted
time: 120ms
memory: 120780kb
input:
315618
output:
602805814
result:
ok 1 number(s): "602805814"
Test #33:
score: 0
Accepted
time: 179ms
memory: 120792kb
input:
1130465
output:
898203793
result:
ok 1 number(s): "898203793"
Test #34:
score: 0
Accepted
time: 484ms
memory: 120840kb
input:
4399723
output:
101317224
result:
ok 1 number(s): "101317224"
Test #35:
score: 0
Accepted
time: 517ms
memory: 120776kb
input:
4804460
output:
114947085
result:
ok 1 number(s): "114947085"
Test #36:
score: 0
Accepted
time: 541ms
memory: 120776kb
input:
4995726
output:
460040939
result:
ok 1 number(s): "460040939"
Test #37:
score: 0
Accepted
time: 559ms
memory: 120820kb
input:
4999919
output:
780785591
result:
ok 1 number(s): "780785591"
Test #38:
score: 0
Accepted
time: 551ms
memory: 120716kb
input:
4999999
output:
742624725
result:
ok 1 number(s): "742624725"