Data commit

Task/Entropy/D/entropy.d

@@ -0,0 +1,16 @@
+import std.stdio, std.algorithm, std.math;
+
+double entropy(T)(T[] s)
+pure nothrow if (__traits(compiles, s.sort())) {
+    immutable sLen = s.length;
+    return s
+           .sort()
+           .group
+           .map!(g => g[1] / double(sLen))
+           .map!(p => -p * p.log2)
+           .sum;
+}
+
+void main() {
+    "1223334444"d.dup.entropy.writeln;
+}