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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
#748795#6137. Sub-cycle Graphtassei903#TL 40ms18140kbPython31.1kb2024-11-14 21:28:222024-11-14 21:28:26

Judging History

你现在查看的是最新测评结果

  • [2024-11-14 21:28:26]
  • 评测
  • 测评结果:TL
  • 用时:40ms
  • 内存:18140kb
  • [2024-11-14 21:28:22]
  • 提交

answer

mod = 10 ** 9 + 7
nn = 100000
fact = [1] * nn
for i in range(nn - 1):
    fact[i + 1] = fact[i] * (i + 1) % mod
invfact = [1] * nn
invfact[nn - 1] = pow(fact[nn - 1], mod - 2, mod)
for i in range(nn - 1)[::-1]:
    invfact[i] = invfact[i + 1] * (i + 1) % mod
 
def binom(x, y):
    if x < 0 or y < 0 or x - y < 0:
        return 0
    return fact[x] * invfact[y] % mod * invfact[x - y] % mod

def greedy(n, m):
    
    if m > n:
        return 0
    elif m == n:
        return fact[n-1] * pow(2, mod-2, mod) % mod
    g = [0] * (n + 1)
    g[0] = 1
    for _ in range(n-m):
        ng = [0] * (n + 1)
        for i in range(n):
            for j in range(1, n - i + 1):
                if j > 1:
                    ng[i+j] += g[i] * j * pow(2 * (i + j), mod-2, mod) % mod
                else:
                    ng[i+j] += g[i] * pow(i + 1, mod-2, mod) % mod
                ng[i+j] %= mod
        g = ng
        # print(g)
    return fact[n] * g[n] % mod

for _ in range(int(input())):
    n, m = map(int, input().split())
    print(greedy(n, m))

詳細信息

Test #1:

score: 100
Accepted
time: 40ms
memory: 18140kb

input:

3
4 2
4 3
5 3

output:

15
12
90

result:

ok 3 number(s): "15 12 90"

Test #2:

score: -100
Time Limit Exceeded

input:

17446
3 0
3 1
3 2
3 3
4 0
4 1
4 2
4 3
4 4
5 0
5 1
5 2
5 3
5 4
5 5
6 0
6 1
6 2
6 3
6 4
6 5
6 6
7 0
7 1
7 2
7 3
7 4
7 5
7 6
7 7
8 0
8 1
8 2
8 3
8 4
8 5
8 6
8 7
8 8
9 0
9 1
9 2
9 3
9 4
9 5
9 6
9 7
9 8
9 9
10 0
10 1
10 2
10 3
10 4
10 5
10 6
10 7
10 8
10 9
10 10
11 0
11 1
11 2
11 3
11 4
11 5
11 6
11 7
11...

output:

1
3
3
1
1
6
15
12
3
1
10
45
90
60
12
1
15
105
375
630
360
60
1
21
210
1155
3465
5040
2520
360
1
28
378
2940
13545
35280
45360
20160
2520
1
36
630
6552
42525
170100
393120
453600
181440
20160
1
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
181440
1
55
1485
24750
273735
2047815
10239075
3...

result: