Combinations with repetitions: Difference between revisions

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@@ Line 2,899: / Line 2,899: @@
 =={{header|Sidef}}==
 {{trans|Perl}}
-<lang ruby>func p (n, a, l) { n>0 ? (l.range.map{p(n-1, a+[l[_]], l.ft(_))}) : a };
+<lang ruby>func cwr (n, l, a = []) {
-func f (n)       { n>0 ? (n * f(n - 1)) : 1 };
+    n>0 ? (^l -> map {|k| __FUNC__(n-1, l.slice(k), [a..., l[k]]) }) : a
-func n (n, m)    { f(n + m - 1) / f(n) / f(m - 1) };
-p(2, [], %w(iced jam plain)).each { |a|
-    say a.map{|pair| pair.join(" ")}.join("\n");
 }
+cwr(2, %w(iced jam plain)).each {|a|
-printf("\nThere are %d ways to pick 7 out of 10\n", n(7, 10));</lang>
+    say a.map{ .join(' ') }.join("\n")
+}</lang>
+Also built-in:
+<lang ruby>%w(iced jam plain).combinations_with_repetition(2, {|*a|
+    say a.join(' ')
+})</lang>
 {{out}}
@@ Line 2,917: / Line 2,921: @@
 jam plain
 plain plain
+</pre>
+Efficient count of the total number of combinations with repetition:
-There are 11440 ways to pick 7 out of 10
+<lang ruby>func cwr_count (n, m) { binomial(n + m - 1, m) }
+printf("\nThere are %s ways to pick 7 out of 10 with repetition\n", cwr_count(10, 7))</lang>
+{{out}}
+<pre>
+There are 11440 ways to pick 7 out of 10 with repetition
 </pre>