AoC 2022 D4: Camp Cleanup

| Problem statement | Source code | Tags: Data structures

← Previous Back to AoC Index Next →

Part 1

Let the two ranges be $(a_1, b_1)$ and $(a_2, b_2)$. One range fully contains the other if and only if $a_1 \leq a_2$ and $b_1 \geq b_2$, or $a_2 \leq a_1$ and $b_2 \geq b_1$.

contain :: [(Int, Int)] -> Bool
contain [(a1, b1), (a2, b2)] = (a1 <= a2 && b1 >= b2) || (a1 >= a2 && b1 <= b2)

GHC.Utils.Misc has a useful function count, so the answer is just count contain lines.

Part 2

Two ranges $(a_1, b_1)$ and $(a_2, b_2)$ overlap if and only if they do not satisfy the condition $b_1 < a_2$ (range 1 is entirely less than 2) or $b_2 < a_1$ (range 2 is entirely less than 1). In other words, we need $b_1 \geq a_2$ and $b_2 \geq a_1$.

overlap [(a1, b1), (a2, b2)] = b1 >= a2 && b2 >= a1

← Previous Back to AoC Index Next →