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* array.c (rb_ary_repeated_combination): Support for repeated_combination.size

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[Feature #6636]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37504 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
marcandre 2012-11-06 17:11:51 +00:00
parent 68c90c4a2d
commit ba59365db9
2 changed files with 17 additions and 1 deletions
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13
array.c
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@ -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: * call-seq:
* ary.repeated_combination(n) { |c| block } -> ary * ary.repeated_combination(n) { |c| block } -> ary
@ -4678,7 +4689,7 @@ rb_ary_repeated_combination(VALUE ary, VALUE num)
long n, i, len; long n, i, len;
n = NUM2LONG(num); /* Combination size from argument */ 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); len = RARRAY_LEN(ary);
if (n < 0) { if (n < 0) {
/* yield nothing */ /* yield nothing */

5
test/ruby/test_enumerator.rb
View File

@ -450,6 +450,11 @@ class TestEnumerator < Test::Unit::TestCase
check_consistency_for_combinatorics(:repeated_permutation) check_consistency_for_combinatorics(:repeated_permutation)
assert_equal 291733167875766667063796853374976, assert_equal 291733167875766667063796853374976,
(1..42).to_a.repeated_permutation(20).size # 42 ** 20 (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
end end