diff options
| -rw-r--r-- | array.c | 13 | ||||
| -rw-r--r-- | test/ruby/test_enumerator.rb | 5 |
2 files changed, 17 insertions, 1 deletions
@@ -4645,6 +4645,17 @@ rcombinate0(long n, long r, long *p, long index, long rest, VALUE values) } } +static VALUE +rb_ary_repeated_combination_size(VALUE ary, VALUE args) +{ + long n = RARRAY_LEN(ary); + long k = NUM2LONG(RARRAY_PTR(args)[0]); + if (k == 0) { + return LONG2FIX(1); + } + return binomial_coefficient(k, n + k - 1); +} + /* * call-seq: * ary.repeated_combination(n) { |c| block } -> ary @@ -4678,7 +4689,7 @@ rb_ary_repeated_combination(VALUE ary, VALUE num) long n, i, len; n = NUM2LONG(num); /* Combination size from argument */ - RETURN_ENUMERATOR(ary, 1, &num); /* Return Enumerator if no block */ + RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_combination_size); /* Return enumerator if no block */ len = RARRAY_LEN(ary); if (n < 0) { /* yield nothing */ diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb index 1c04a05bb0..93d46a6c23 100644 --- a/test/ruby/test_enumerator.rb +++ b/test/ruby/test_enumerator.rb @@ -450,6 +450,11 @@ class TestEnumerator < Test::Unit::TestCase check_consistency_for_combinatorics(:repeated_permutation) assert_equal 291733167875766667063796853374976, (1..42).to_a.repeated_permutation(20).size # 42 ** 20 + + check_consistency_for_combinatorics(:repeated_combination) + assert_equal 28258808871162574166368460400, + (1..59).to_a.repeated_combination(42).size + # 1.upto(100).inject(:*) / 1.upto(42).inject(:*) / 1.upto(58).inject(:*) end end |