2022/day09.awk


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BEGIN {
	t1[0,0] = 1;
	t9[0,0] = 1;
}
function abs(x) {
	return (x < 0 ? -x : x);
}
function step(k) {
	rx = kx[k] - kx[k-1];
	ry = ky[k] - ky[k-1];
	if (abs(rx) <= 1 && abs(ry) <= 1) return;
	if (rx == 0) {
		ky[k] += (ry < 0 ? +1 : -1);
	} else if (ry == 0) {
		kx[k] += (rx < 0 ? +1 : -1);
	} else {
		kx[k] += (rx < 0 ? +1 : -1);
		ky[k] += (ry < 0 ? +1 : -1);
	}
}
{
	dx = 0;
	dy = 0;
	if ($1 == "U") dy = -1;
	if ($1 == "D") dy = +1;
	if ($1 == "L") dx = -1;
	if ($1 == "R") dx = +1;
	for (i = 1; i <= $2; ++i) {
		kx[0] += dx;
		ky[0] += dy;
		for (k = 1; k <= 9; ++k) {
			step(k);
		}
		t1[+kx[1],+ky[1]] = 1;
		t9[+kx[9],+ky[9]] = 1;
	}
}
END {
	for (i in t1) {
		sum1++;
	}
	print sum1;
	for (i in t9) {
		sum9++;
	}
	print sum9;
}