Merge pull request #4 from palinkiewicz/2023_d03

palinkiewicz · web-flow · commit d45790cd4238 · 2023-12-04T18:26:53.000+01:00
2023 Day 03
diff --git a/README.md b/README.md
@@ -5,8 +5,8 @@ In this repository, I am going to store my solutions to the [Advent of Code](htt
 I started taking part in the event in 2023 but may also consider doing tasks from the previous years.
 
 ## 2023
-|                                              |                                              My solution                                              |
-| -------------------------------------------- | ----------------------------------------------------------------------------------------------------- |
+|                                              | My solution                                                                                           |
+| -------------------------------------------- |-------------------------------------------------------------------------------------------------------|
 | [Day 1](https://adventofcode.com/2023/day/1) | [Solution](https://github.com/palinkiewicz/adventofcode-kotlin/blob/master/adventofcode2023/Day01.kt) |
 | [Day 2](https://adventofcode.com/2023/day/2) | [Solution](https://github.com/palinkiewicz/adventofcode-kotlin/blob/master/adventofcode2023/Day02.kt) |
-| [Day 3](https://adventofcode.com/2023/day/3) | Soon |
+| [Day 3](https://adventofcode.com/2023/day/3) | [Solution](https://github.com/palinkiewicz/adventofcode-kotlin/blob/master/adventofcode2023/Day03.kt) |
diff --git a/adventofcode2023/Day03.kt b/adventofcode2023/Day03.kt
@@ -0,0 +1,126 @@
+package adventofcode2023
+
+import java.io.File
+
+object Day03 {
+    fun part1(inputs: List<String>) {
+        val firstDigitChecks = setOf(
+            Pair(-1, 0),
+            Pair(-1, -1),
+            Pair(0, -1),
+            Pair(-1, 1),
+            Pair(0, 1)
+        )
+        val centralDigitChecks = setOf(
+            Pair(0, 1),
+            Pair(0, -1)
+        )
+        val lastDigitChecks = setOf(
+            Pair(1, 0),
+            Pair(1, 1),
+            Pair(0, 1),
+            Pair(1, -1),
+            Pair(0, -1)
+        )
+
+        fun checkPositions(x: Int, y: Int, checks: Set<Pair<Int, Int>>): Boolean {
+            return checks.any {
+                val checkX = x + it.first
+                val checkY = y + it.second
+
+                if (checkX < 0 || checkY < 0
+                    || checkX >= inputs[0].length || checkY >= inputs.size
+                ) {
+                    false
+                } else {
+                    inputs[checkY][checkX] != '.'
+                }
+            }
+        }
+
+        fun checkPartNumberDigit(x: Int, y: Int): Boolean =
+            (x > 0 && !inputs[y][x - 1].isDigit() && checkPositions(x, y, firstDigitChecks)
+                    || x < inputs[0].length - 1 && !inputs[y][x + 1].isDigit() && checkPositions(x, y, lastDigitChecks)
+                    || checkPositions(x, y, centralDigitChecks))
+
+        var sum = 0
+
+        for (y in inputs.indices) {
+            var x = 0
+            while (x < inputs[0].length) {
+                if (inputs[y][x].isDigit()) {
+                    var isPartNumber = checkPartNumberDigit(x, y)
+                    var number = inputs[y][x].toString()
+
+                    while (x < inputs[0].length - 1 && inputs[y][x + 1].isDigit()) {
+                        x++
+                        number += inputs[y][x]
+                        if (!isPartNumber && checkPartNumberDigit(x, y)) isPartNumber = true
+                    }
+
+                    if (isPartNumber) sum += number.toInt()
+                }
+                x++
+            }
+        }
+
+        println(sum)
+    }
+
+    fun part2(inputs: List<String>) {
+        fun getAsteriskPositions(): List<Pair<Int, Int>> {
+            val asteriskPositions = mutableListOf<Pair<Int, Int>>()
+            for (y in inputs.indices) {
+                for (x in inputs[0].indices) {
+                    if (inputs[y][x] == '*') {
+                        asteriskPositions.add(Pair(x, y))
+                    }
+                }
+            }
+            return asteriskPositions
+        }
+
+        fun getPartNumber(x: Int, y: Int): Pair<Int, Int>? {
+            if (inputs[y][x].isDigit()) {
+                var number = inputs[y][x].toString()
+                var checkLeft = x - 1
+                var checkRight = x + 1
+
+                while (checkLeft >= 0 && inputs[y][checkLeft].isDigit()) {
+                    number = inputs[y][checkLeft] + number
+                    checkLeft--
+                }
+                while (checkRight < inputs[0].length && inputs[y][checkRight].isDigit()) {
+                    number += inputs[y][checkRight]
+                    checkRight++
+                }
+
+                return Pair(checkLeft * y, number.toInt())
+            }
+            return null
+        }
+
+        println(getAsteriskPositions().sumOf { // first: x, second: y
+            val partNumbers = mutableListOf<Pair<Int, Int>>()
+
+            for (i in -1..1) {
+                for (j in -1..1) {
+                    val number = getPartNumber(it.first + j, it.second + i)
+
+                    if (number != null && !partNumbers.contains(number)) {
+                        partNumbers.add(number)
+                    }
+                }
+            }
+
+            if (partNumbers.size == 2) partNumbers[0].second * partNumbers[1].second else 0
+        })
+    }
+
+}
+
+fun main() {
+    val inputs = File("resources/adventofcode2023/Day03.txt").readLines()
+    Day03.part1(inputs)
+    Day03.part2(inputs)
+}
diff --git a/resources/adventofcode2023/Day03.txt b/resources/adventofcode2023/Day03.txt
