From 790b8e34f92680e4d0b52f2fbcb5654420c20caf Mon Sep 17 00:00:00 2001
From: June McEnroe <june@causal.agency>
Date: Fri, 9 Dec 2022 11:12:22 -0500
Subject: Solve day 9 part 2

---
 2022/day09.awk | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/2022/day09.awk b/2022/day09.awk
index 95e4fb4..da142a4 100644
--- a/2022/day09.awk
+++ b/2022/day09.awk
@@ -1,23 +1,22 @@
 BEGIN {
-	t[0,0] = 1;
+	t1[0,0] = 1;
+	t9[0,0] = 1;
 }
 function abs(x) {
-	if (x < 0) return -x;
-	return x;
+	return (x < 0 ? -x : x);
 }
-function step() {
-	rx = tx-hx;
-	ry = ty-hy;
+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) {
-		ty += (ry < 0 ? +1 : -1);
+		ky[k] += (ry < 0 ? +1 : -1);
 	} else if (ry == 0) {
-		tx += (rx < 0 ? +1 : -1);
+		kx[k] += (rx < 0 ? +1 : -1);
 	} else {
-		tx += (rx < 0 ? +1 : -1);
-		ty += (ry < 0 ? +1 : -1);
+		kx[k] += (rx < 0 ? +1 : -1);
+		ky[k] += (ry < 0 ? +1 : -1);
 	}
-	t[tx,ty] = 1;
 }
 {
 	dx = 0;
@@ -27,14 +26,22 @@ function step() {
 	if ($1 == "L") dx = -1;
 	if ($1 == "R") dx = +1;
 	for (i = 1; i <= $2; ++i) {
-		hx += dx;
-		hy += dy;
-		step();
+		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 t) {
-		sum++;
+	for (i in t1) {
+		sum1++;
 	}
-	print sum;
+	print sum1;
+	for (i in t9) {
+		sum9++;
+	}
+	print sum9;
 }
-- 
cgit 1.4.1