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

22 lines
756 B
D

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[]);
}