Combinations: Difference between revisions

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@@ Line 510: / Line 510: @@
       (printf "%s " n))
     (printf "%n")))</lang>
+=={{header|CoffeeScript}}==
+Basic backtracking solution.
+<lang coffeescript>
+combinations = (n, p) ->
+  return [ [] ] if p == 0
+  i = 0
+  combos = []
+  combo = []
+  while combo.length < p
+    if i < n
+      combo.push i
+      i += 1
+    else
+      break if combo.length == 0
+      i = combo.pop() + 1
+    if combo.length == p
+      combos.push clone combo
+      i = combo.pop() + 1
+  combos
+clone = (arr) -> (n for n in arr)
+N = 5
+for i in [0..N]
+  console.log "------ #{N} #{i}"
+  for combo in combinations N, i
+    console.log combo
+</lang>
+output
+<lang>> coffee combo.coffee
+------ 5 0
+[]
+------ 5 1
+[ 0 ]
+[ 1 ]
+[ 2 ]
+[ 3 ]
+[ 4 ]
+------ 5 2
+[ 0, 1 ]
+[ 0, 2 ]
+[ 0, 3 ]
+[ 0, 4 ]
+[ 1, 2 ]
+[ 1, 3 ]
+[ 1, 4 ]
+[ 2, 3 ]
+[ 2, 4 ]
+[ 3, 4 ]
+------ 5 3
+[ 0, 1, 2 ]
+[ 0, 1, 3 ]
+[ 0, 1, 4 ]
+[ 0, 2, 3 ]
+[ 0, 2, 4 ]
+[ 0, 3, 4 ]
+[ 1, 2, 3 ]
+[ 1, 2, 4 ]
+[ 1, 3, 4 ]
+[ 2, 3, 4 ]
+------ 5 4
+[ 0, 1, 2, 3 ]
+[ 0, 1, 2, 4 ]
+[ 0, 1, 3, 4 ]
+[ 0, 2, 3, 4 ]
+[ 1, 2, 3, 4 ]
+------ 5 5
+[ 0, 1, 2, 3, 4 ]
+</lang>
 =={{header|Common Lisp}}==