A-M baby

Task/Huffman-coding/D/huffman-coding.d

@@ -0,0 +1,21 @@
+import std.stdio, std.algorithm, std.typecons, std.container,std.array;
+
+auto encode(T)(Group!("a == b", T[]) sf) {
+    auto heap = sf.map!(s => tuple(s[1], [tuple(s[0], "")]))
+                .array.heapify!q{b < a};
+
+    while (heap.length > 1) {
+        auto lo = heap.front; heap.removeFront;
+        auto hi = heap.front; heap.removeFront;
+        foreach (ref pair; lo[1]) pair[1] = '0' ~ pair[1];
+        foreach (ref pair; hi[1]) pair[1] = '1' ~ pair[1];
+        heap.insert(tuple(lo[0] + hi[0], lo[1] ~ hi[1]));
+    }
+    return heap.front[1].schwartzSort!q{tuple(a[1].length, a[0])};
+}
+
+void main() {
+    auto s = "this is an example for huffman encoding"d;
+    foreach (p; s.dup.sort().release.group.encode)
+        writefln("'%s'  %s", p[]);
+}