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comparison 2017/day10.d @ 10:bd993cf00e2f

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day 10
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Mon, 11 Dec 2017 19:50:57 -0500
parents
children 990a4fa2aebe
comparison
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9:18e7ffa83a14 10:bd993cf00e2f
1 import std.stdio;
2 import std.range: iota, array, chunks;
3 import std.algorithm: invert=reverse, map, reduce;
4 import std.conv: to;
5 import std.format: format;
6 import std.string: join;
7
8 void reverse(int Size)(ref int[Size] twine, int a, int b) {
9 a = a % Size;
10 b = b % Size;
11 if (a <= b) {
12 invert(twine[a..b]);
13 }
14 else {
15 auto result = twine[a..$] ~ twine[0..b];
16 invert(result);
17 twine[a..$] = result[0..Size-a];
18 twine[0..b] = result[Size-a..$];
19 }
20 }
21
22 auto knotUp(int Size)(int[] lengths, int[Size] twine) {
23 static pos = 0, skip = 0;
24 foreach(length; lengths) {
25 reverse(twine, pos, pos+length);
26 pos += length + skip;
27 skip++;
28 }
29 return twine;
30 }
31
32 auto getHash(int Size, int Rounds, int ChunkSize)(int[] lengths)
33 if( Size % ChunkSize == 0)
34 {
35 int[Size] twine = iota(0, Size).array;
36 for(int i = 0; i < Rounds; i++) {
37 twine = knotUp(lengths, twine);
38 }
39 return twine.array.chunks(ChunkSize).map!(
40 x => format("%02x", reduce!((a,b) => a ^ b)(x[0], x[1..$]))
41 ).join;
42 }
43
44 void main(string[] args){
45 int[] lengths = to!(int[])(cast(ubyte[]) args[1]) ~ [17, 31, 73, 47, 23];
46 auto hash = getHash!(256, 64, 16)(lengths);
47 writeln(hash);
48 }