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Damn you, Day 13.

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This commit is contained in:
Chris Hodges 2023-12-14 21:58:42 +01:00
parent b3f648a01e
commit 3586f49f91
1 changed files with 71 additions and 46 deletions
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117
src/aoc2023/Day13.kt
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@ -3,7 +3,6 @@ package aoc2023
import CharGrid
import println
import readInput
import kotlin.math.min
/*
--- Day 13: Point of Incidence ---
@ -78,66 +77,62 @@ fun main() {
#....#..#
"""
fun mirrored(bits: IntArray, size: Int): Int {
for (p1 in 0 until size - 1) {
var p2 = 0
var match = true
while (p1 >= p2 && p1 + p2 + 1 < size) {
if (bits[p1 - p2] != bits[p1 + p2 + 1]) {
match = false
break
}
p2++
}
if (match) return p1 + 1
}
return 0
}
fun smudged(bits: IntArray, size: Int): Int {
for (p1 in 0 until size - 1) {
var smudges = 0
var p2 = 0
while (p1 >= p2 && p1 + p2 + 1 < size) {
smudges += (bits[p1 - p2] xor bits[p1 + p2 + 1]).countOneBits()
if (smudges > 1) break
p2++
}
if (smudges == 1) return p1 + 1
}
return 0
}
fun part1(input: List<String>): Int {
val tmpList = ArrayList<String>()
var result = 0
for (i in input) {
for ((idx, i) in input.withIndex()) {
if (i.isNotBlank()) {
tmpList.add(i)
} else {
}
if (i.isBlank() || (idx == input.lastIndex && tmpList.isNotEmpty())) {
val grid = CharGrid(tmpList)
val vertSA = IntArray(grid.width)
val vertSARev = IntArray(grid.width)
val horzSA = IntArray(grid.height)
val horzSARev = IntArray(grid.height)
for (c in 0 until grid.width) {
for (r in 0 until grid.height) {
val revR = grid.height - 1 - r
vertSA[c] = vertSA[c] * 2 + (if (grid[c, r] == '#') 1 else 0)
vertSARev[c] = vertSARev[c] * 2 + if (grid[c, revR] == '#') 1 else 0
}
}
for (r in 0 until grid.height) {
for (c in 0 until grid.width) {
val revC = grid.width - 1 - c
horzSA[r] = horzSA[r] * 2 + if (grid[c, r] == '#') 1 else 0
horzSARev[r] = horzSARev[r] * 2 + if (grid[revC, r] == '#') 1 else 0
}
}
var href = 0
for (sh in 1 until grid.height-1) {
val mask = ((1 shl grid.height) - 1) shr sh
var found = false
for (c in 0 until grid.width) {
if ((vertSA[c] shr sh) and mask != vertSARev[c] and mask) {
found = false
break
}
}
if (found) {
href = sh
}
}
var vref = 0
for (sh in 1 until grid.width-1) {
val width = min(sh, grid.width-sh)
val mask = (1 shl width) - 1
var found = false
for (r in 0 until grid.height) {
if (((horzSA[r] shr ((sh-width).coerceAtLeast(0))) and mask) != ((horzSARev[r] shr (grid.width-width).coerceAtMost(0)) and mask)) {
found = false
break
}
}
if (found) {
vref = sh
}
}
for(r in 0 until grid.height)
{
println(horzSA[r].toString(2).padStart(grid.width, '0') + " " + horzSARev[r].toString(2).padStart(grid.width, '0'))
val vref = mirrored(vertSA, grid.width)
if (vref > 0) {
result += vref
} else {
result += mirrored(horzSA, grid.height) * 100
}
tmpList.clear()
@ -147,7 +142,37 @@ fun main() {
}
fun part2(input: List<String>): Int {
return 0
val tmpList = ArrayList<String>()
var result = 0
for ((idx, i) in input.withIndex()) {
if (i.isNotBlank()) {
tmpList.add(i)
}
if (i.isBlank() || (idx == input.lastIndex && tmpList.isNotEmpty())) {
val grid = CharGrid(tmpList)
val vertSA = IntArray(grid.width)
val horzSA = IntArray(grid.height)
for (c in 0 until grid.width) {
for (r in 0 until grid.height) {
vertSA[c] = vertSA[c] * 2 + (if (grid[c, r] == '#') 1 else 0)
}
}
for (r in 0 until grid.height) {
for (c in 0 until grid.width) {
horzSA[r] = horzSA[r] * 2 + if (grid[c, r] == '#') 1 else 0
}
}
val vref = smudged(vertSA, grid.width)
if (vref > 0) {
result += vref
} else {
result += smudged(horzSA, grid.height) * 100
}
tmpList.clear()
}
}
return result
}
// test if implementation meets criteria from the description, like:
@ -157,8 +182,8 @@ fun main() {
println("Part 1 Test: $testInputPart1Result")
val testInputPart2Result = part2(testInput)
println("Part 2 Test: $testInputPart2Result")
check(testInputPart1Result == 0)
check(testInputPart2Result == 0)
check(testInputPart1Result == 405)
check(testInputPart2Result == 400)
val input = readInput("aoc2023/Day13")
part1(input).println()