8ad362b140
* Additionally modified solution for Part 1 due to changed signature of getNumberAndBlank
124 lines
2.7 KiB
Go
124 lines
2.7 KiB
Go
package main
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import (
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"errors"
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"strconv"
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"strings"
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"unicode"
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"github.com/jpillora/puzzler/harness/aoc"
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)
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func main() {
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aoc.Harness(run)
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}
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func getNumberAndBlank(schema [][]rune, x int, y int) (int, error) {
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if x < 0 || x >= len(schema) || y < 0 || y >= len(schema[x]) {
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// Out of bounds
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return 0, errors.New("out of bounds")
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}
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if !unicode.IsNumber(schema[x][y]) {
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// Not a number to start
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return 0, errors.New("is not number")
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}
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// Moves along y to find the first character...
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firstFound := false
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for !firstFound {
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if y == 0 || !unicode.IsNumber(schema[x][y-1]) {
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firstFound = true
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} else {
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y -= 1
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}
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}
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// then assemble
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numStr := ""
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for y < len(schema[x]) && unicode.IsNumber(schema[x][y]) {
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numStr += string(schema[x][y])
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schema[x][y] = '.'
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y += 1
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}
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num, _ := strconv.Atoi(numStr)
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return num, nil
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}
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// on code change, run will be executed 4 times:
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// 1. with: false (part1), and example input
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// 2. with: true (part2), and example input
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// 3. with: false (part1), and user input
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// 4. with: true (part2), and user input
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// the return value of each run is printed to stdout
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func run(part2 bool, input string) any {
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// Assemble schematic
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schematic := make([][]rune, 0)
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for _, line := range strings.Split(input, "\n") {
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if line != "" {
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schematic = append(schematic, []rune(line))
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}
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}
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if part2 {
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// Go through array, if we find a * character, find adjacent gears (we cannot blank permanently)
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gearSum := 0
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for x, _ := range schematic {
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for y, _ := range schematic[x] {
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if schematic[x][y] != '*' {
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// Cannot be a gear
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continue
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}
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adjParts := make([]int, 0)
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// Else, it's a symbol! Go around and, if there are any numbers, assemble them
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// must make a copy of the schematic so as to only blank locally
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tempSchema := schematic
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for xi := x - 1; xi < x+2; xi++ {
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for yi := y - 1; yi < y+2; yi++ {
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part, err := getNumberAndBlank(tempSchema, xi, yi)
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if err == nil {
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adjParts = append(adjParts, part)
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}
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}
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}
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if len(adjParts) == 2 {
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// Is a gear
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gearRatio := adjParts[0] * adjParts[1]
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gearSum += gearRatio
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}
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}
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}
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return gearSum
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}
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// solve part 1 here
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// Go through array, if we find a non-number non-period, find all adjacent numbers and then turn those to periods
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engineSum := 0
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for x, _ := range schematic {
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for y, _ := range schematic[x] {
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if unicode.IsNumber(schematic[x][y]) || schematic[x][y] == '.' {
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continue
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}
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// Else, it's a symbol! Go around and, if there are any numbers, assemble them
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for xi := x - 1; xi < x+2; xi++ {
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for yi := y - 1; yi < y+2; yi++ {
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part, err := getNumberAndBlank(schematic, xi, yi)
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if err == nil {
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engineSum += part
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}
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}
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}
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}
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}
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return engineSum
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}
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