Problem Statement
Determine the number of mega cool numbers of power A that contain exactly N digits (with no leading zeroes). Return this number modulo 1,000,000,007.
Definition
- Class:
- MegaCoolNumbers
- Method:
- count
- Parameters:
- int, int
- Returns:
- int
- Method signature:
- int count(int N, int A)
- (be sure your method is public)
Constraints
- A and N will be between 1 and 1,000, inclusive.
Examples
3
1
Returns: 25
3
5
Returns: 0
10
6
Returns: 0
10
2
Returns: 643
6
10
Returns: 0
9
4
Returns: 13946
8
10
Returns: 0
8
5
Returns: 0
8
6
Returns: 0
6
10
Returns: 0
7
8
Returns: 0
29
9
Returns: 1550927
17
7
Returns: 154272
29
7
Returns: 13904532
13
2
Returns: 744
4
10
Returns: 0
33
10
Returns: 0
10
3
Returns: 7502
8
9
Returns: 0
27
9
Returns: 679757
56
4
Returns: 4328198
28
1
Returns: 9
64
2
Returns: 2580
28
6
Returns: 8752247
51
5
Returns: 38201689
65
10
Returns: 0
8
1
Returns: 11
52
10
Returns: 0
22
6
Returns: 2125867
80
1
Returns: 9
302
2
Returns: 11148
282
9
Returns: 678308819
28
10
Returns: 0
35
2
Returns: 1536
369
6
Returns: 528884859
194
7
Returns: 927974911
140
4
Returns: 62139602
231
7
Returns: 603901423
258
5
Returns: 901374186
142
7
Returns: 24704033
197
3
Returns: 1726380
23
7
Returns: 2386305
238
1
Returns: 9
192
5
Returns: 387626608
53
2
Returns: 2184
505
4
Returns: 766538468
7
7
Returns: 0
443
4
Returns: 873279675
548
8
Returns: 484028533
65
2
Returns: 2616
649
8
Returns: 330601169
138
4
Returns: 59572172
832
3
Returns: 29486040
455
6
Returns: 239344926
495
7
Returns: 70673564
139
9
Returns: 589827333
350
5
Returns: 429601569
270
10
Returns: 0
452
10
Returns: 0
988
1
Returns: 9
836
3
Returns: 29768256
63
9
Returns: 992381041
308
8
Returns: 267850613
400
7
Returns: 53957028
43
1
Returns: 9
844
1
Returns: 9
977
6
Returns: 928100631
149
10
Returns: 0
252
4
Returns: 351189986
574
2
Returns: 20940
216
9
Returns: 190312172
723
7
Returns: 873242124
582
1
Returns: 9
176
8
Returns: 230110582
904
4
Returns: 714463437
993
4
Returns: 804165142
315
10
Returns: 0
706
4
Returns: 511679299
190
1
Returns: 9
664
10
Returns: 0
554
4
Returns: 645406871
96
1
Returns: 9
963
7
Returns: 350994727
918
3
Returns: 35849868
743
7
Returns: 512504519
440
10
Returns: 0
420
2
Returns: 15396
740
5
Returns: 553012949
46
7
Returns: 326423760
471
9
Returns: 844419866
729
6
Returns: 752357982
216
1
Returns: 9
604
2
Returns: 22020
733
9
Returns: 153995176
23
2
Returns: 1104
908
1
Returns: 9
726
4
Returns: 164721112
852
9
Returns: 400626524
22
3
Returns: 29580
1000
9
Returns: 528971249
1
1
Returns: 9
There 9 such numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9.
2
1
Returns: 45
Any two-digit number with non-decreasing digits will be a mega cool number of power 1.
2
2
Returns: 0
There are no such numbers.
10
3
Returns: 7502
1000
1000
Returns: 0
1000
980
Returns: 0
999
9
Returns: 604032056
1000
999
Returns: 0