tasks a-s

Task/Permutations/D/permutations-1.d

@@ -0,0 +1,21 @@
+import std.stdio: writeln;
+
+T[][] permutations(T)(T[] items) {
+    T[][] result;
+
+    void perms(T[] s, T[] prefix=[]) {
+        if (s.length)
+            foreach (i, c; s)
+               perms(s[0 .. i] ~ s[i+1 .. $], prefix ~ c);
+        else
+            result ~= prefix;
+    }
+
+    perms(items);
+    return result;
+}
+
+void main() {
+    foreach (p; permutations([1, 2, 3]))
+        writeln(p);
+}