Initial data commit

Task/Gray-code/D/gray-code-1.d

@@ -0,0 +1,22 @@
+uint grayEncode(in uint n) pure nothrow @nogc {
+    return n ^ (n >> 1);
+}
+
+uint grayDecode(uint n) pure nothrow @nogc {
+    auto p = n;
+    while (n >>= 1)
+        p ^= n;
+    return p;
+}
+
+void main() {
+    import std.stdio;
+
+    " N     N2      enc     dec2 dec".writeln;
+    foreach (immutable n; 0 .. 32) {
+        immutable g = n.grayEncode;
+        immutable d = g.grayDecode;
+        writefln("%2d: %5b => %5b => %5b: %2d", n, n, g, d, d);
+        assert(d == n);
+    }
+}