same code, just a little shorter.
usage of ".array"
more UFCS
replaced cast with ".to"
---------------8><---------------------------------------
import std.stdio, std.conv;
import std.algorithm, std.algorithm.searching, std.range;
import std.ascii, std.string : countchars;
int let2int(char c) {
return (c - 'a').to!int;
}
char int2let(int n) {
return (n >= 0 ? 'a' + n : 'z' + n + 1).to!char;
}
char shift(char c, int n) {
return c.isLower ? ((c.let2int + n) % 26).int2let : c;
}
auto encode(int n, char[] s) {
return s.map!(c => c.to!char.shift(n));
}
alias decode = (int n, char[] s) { return encode(-n, s); };
auto positions(float x, float[] fl) {
return fl.zip(fl.length.iota).filter!(t => t[0]==x).map!(t =>
t[1]);
}
float chisqr(float[] os, float[] es) {
return os.zip(es).map!(t => ((t[0]-t[1])^^2)/t[1]).sum;
}
float[] rotate(int n, float[] fl) {
return (fl.drop(n) ~ fl.take(n)).array;
}
string crack(string s) {
auto freqs(char[] s) {
alias cccount = (char c, char[] s) {
return countchars(s, to!string(c)).to!int;
};
alias percent = (int n, int m) { return n / m.to!float * 100;
};
alias lowers = (char[] s) { return count!isLower(s).to!int; };
enum allChars = "abcdefghijklmnopqrstuvwxyz".to!(char[]);
return allChars.map!(a =>
percent(cccount(a.to!char, s), lowers(s)) ).array;
}
// ASCII letters frequency from 'a'..'z'
float[] table = [
8.2, 1.5, 2.8, 4.3, 12.7, 2.2, 2.0, 6.1, 7.0, 0.2, 0.8, 4.0,
2.4,
6.7, 7.5, 1.9, 0.1, 6.0, 6.3, 9.1, 2.8, 1.0, 2.4, 0.2, 2.0,
0.1];
auto table2 = freqs(s.to!(char[]));
auto chitab = table.length.to!uint.iota.map!(
n => n.rotate(table2).chisqr(table)).array;
auto minval = chitab.reduce!min;
auto factor = positions(minval, chitab).front.to!int;
return decode(factor, s.to!(char[])).to!string;
}
void main() {
writeln("wyvnyhttpun pu kshun pz clyf mbu! = ",
crack("wyvnyhttpun pu kshun pz clyf mbu!"));
}
