FP(FP) June entry for thedeemon, v1

stars.d

module main;
import std.stdio, std.algorithm, std.array, std.conv;

immutable mask = 0b11111110000000000000;
alias int[] star;

void main(string[] argv)
{
    star[][int] cells;	
    foreach(s; File("stars.dat", "rt").byLine()) {	   
        int[] coords = s.split().map!(to!int).array();
        int sector = ((coords[0] & mask) << 1) + ((coords[1] & mask) >> 6) + ((coords[2] & mask) >> 13);
        auto a = cells.get(sector, []);
        a ~= coords;
        cells[sector] = a;
    }
    auto nbr = [-1, 0, 1];
    int[] deltas = [];
    foreach(x; nbr)	foreach(y; nbr)	foreach(z; nbr)	deltas ~= (x << 14) + (y << 7) + z;
    long mind = 10^^13;
    star besta=[], bestb=[];
    foreach(cell; cells.byKey()) {
        star[] area = [];
        foreach(delta; deltas) {
            int sector = cell + delta;
            if (sector in cells)
                area ~= cells[sector];
        }
        if (area.length > 1) {
            foreach(a; area)
                foreach(b; area)
                    if (a !is b) {
                        long d = (a[0]-b[0])^^2 + (a[1]-b[1])^^2 + (a[2]-b[2])^^2;
                        if (d < mind) {
                            mind = d;
                            besta = a; bestb = b;
                        }
                    }
        }
    }
    writeln(std.math.sqrt(to!real(mind)), besta, bestb);
}