Data commit

Task/Combinations/Lobster/combinations-1.lobster

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+import std
+
+// combi is an itertor that solves the Combinations problem for iota arrays as stated
+
+def combi(m, n, f):
+    let c = map(n): _
+
+    while true:
+        f(c)
+        var i = n-1
+        c[i] = c[i] + 1
+        if c[i] > m - 1:
+            while c[i] >= m - n + i:
+                i -= 1
+                if i < 0: return
+            c[i] = c[i] + 1
+            while i < n-1:
+                c[i+1] = c[i] + 1
+                i += 1
+
+combi(5, 3): print(_)

Task/Combinations/Lobster/combinations-2.lobster

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+import std
+
+// comba solves the general problem for any values in an input array
+
+def comba<T>(arr: [T], k) -> [[T]]:
+    let ret = []
+    for(arr.length) i:
+        if k == 1:
+            ret.push([arr[i]])
+        else:
+            let sub = comba(arr.slice(i+1, -1), k-1)
+            for(sub) next:
+                next.insert(0, arr[i])
+                ret.push(next)
+    return ret
+
+print comba([0,1,2,3,4], 3)
+print comba(["Crosby", "Stills", "Nash", "Young"], 3)
+// Of course once could use combi to index the input array instead
+var s = ""
+combi(4, 3): s += (map(_) i: ["Crosby", "Stills", "Nash", "Young"][i]) + " "
+print s