2020/03/puzzle-2.awk


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#!/usr/bin/env -S awk -f

BEGIN {
	slope[1] = 1
	slope[2] = 1
	slope[3] = 1
	slope[4] = 1
	slope[5] = 1
}

{
	len = split($0, obs, "")

	right = 1
	for (i = 1; i < 5; i++) {
		if (slope[i] > len)
			slope[i] -= len

		if (obs[slope[i]] == "#")
			count[i]++

		slope[i] += right
		right += 2
	}

	# Specific code for slope 5
	if (NR % 2 == 1) {
		if (slope[5] > len)
			slope[5] -= len

		if (obs[slope[5]++] == "#")
			count[5]++
	}
}

END { print count[1] * count[2] * count[3] * count[4] * count[5] }