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- #!/usr/bin/ruby
- # Daniel "Trizen" Șuteu
- # Date: 15 September 2020
- # https://github.com/trizen
- # Generate "digit sum numbers" with n digits or less.
- # See also:
- # https://oeis.org/A064544
- # https://projecteuler.net/problem=725
- func DS(sum, arr, d, l, callback) {
- if (arr.len >= l) {
- return nil
- }
- if (sum > d) {
- return nil
- }
- if (sum == d) {
- for k in (0..arr.len) {
- var copy = [arr...]
- copy.insert(k, d)
- callback(Num(copy.join))
- }
- }
- for k in (0..9) {
- if (sum + k <= d) {
- DS(sum + k, [arr..., k], d, l, callback)
- }
- }
- }
- var DS_numbers = Set()
- func callback(n) {
- DS_numbers << n
- }
- var n = 3 # n digits or less
- for k in (1..9) {
- DS(0, [], k, n, callback)
- }
- say ("3DS: ", DS_numbers.sort)
- say ("Sum: ", DS_numbers.sum)
- assert_eq(DS_numbers.sum, 63270)
- __END__
- 3DS: [11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 110, 112, 121, 123, 132, 134, 143, 145, 154, 156, 165, 167, 176, 178, 187, 189, 198, 202, 211, 213, 220, 224, 231, 235, 242, 246, 253, 257, 264, 268, 275, 279, 286, 297, 303, 312, 314, 321, 325, 330, 336, 341, 347, 352, 358, 363, 369, 374, 385, 396, 404, 413, 415, 422, 426, 431, 437, 440, 448, 451, 459, 462, 473, 484, 495, 505, 514, 516, 523, 527, 532, 538, 541, 549, 550, 561, 572, 583, 594, 606, 615, 617, 624, 628, 633, 639, 642, 651, 660, 671, 682, 693, 707, 716, 718, 725, 729, 734, 743, 752, 761, 770, 781, 792, 808, 817, 819, 826, 835, 844, 853, 862, 871, 880, 891, 909, 918, 927, 936, 945, 954, 963, 972, 981, 990]
- Sum: 63270
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