tasks a-s

Task/Ordered-Partitions/D/ordered-partitions.d

@@ -0,0 +1,34 @@
+import std.stdio, std.algorithm, std.range, std.array, std.conv;
+// http://rosettacode.org/wiki/Combinations#D
+import combinations4: Comb;
+
+alias int[] iRNG;
+
+iRNG setDiff(iRNG s, iRNG c) {
+    return setDifference(s, c).array();
+}
+
+iRNG[][] orderPart(iRNG blockSize...) {
+    iRNG sum = iota(1, 1 + blockSize.reduce!q{a + b}()).array();
+
+    iRNG[][] p(iRNG s, in iRNG b) {
+        if (b.length == 0)
+            return [[]];
+        iRNG[][] res;
+        foreach (c; Comb.On(s, b[0]))
+            foreach (r; p(setDiff(s, c), b[1 .. $]))
+                res ~= c.dup ~ r;
+        return res;
+    }
+
+    return p(sum, blockSize);
+}
+
+void main(string[] args) {
+    auto b = args.length > 1 ?
+        args[1 .. $].map!(to!int)().array() :
+        [2, 0, 2];
+
+    foreach (p; orderPart(b))
+        writeln(p);
+}