111 lines
2.3 KiB
Go
111 lines
2.3 KiB
Go
package main
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import (
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"fmt"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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func main() {
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inp := h.StdinToStringSlice()
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part1(inp)
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part2(inp)
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}
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func part1(input []string) {
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bm := h.StringSliceToCoordByteMap(input)
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symbols := bm.FindAllNot('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.')
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// Gather a list of numbers that are adjacent to the symbols
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nums := make(map[h.Coordinate]int)
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for k, _ := range symbols {
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wrk := findPartNumsFrom(bm, k)
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for coord, val := range wrk {
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nums[coord] = val
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}
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}
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var sum int
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for _, v := range nums {
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sum += v
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}
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fmt.Println("# Part 1")
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fmt.Println(sum)
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}
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func part2(input []string) {
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bm := h.StringSliceToCoordByteMap(input)
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maybeGears := bm.FindAll('*')
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var ratioSum int
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for _, k := range maybeGears {
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wrk := findPartNumsFrom(bm, k)
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if len(wrk) != 2 {
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// It's not a gear
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continue
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}
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var second bool
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var ratio int
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for _, v := range wrk {
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if !second {
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ratio += v
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second = true
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} else {
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ratio *= v
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}
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}
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ratioSum += ratio
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}
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fmt.Println("# Part 2")
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fmt.Println(ratioSum)
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}
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func findPartNumsFrom(m h.CoordByteMap, c h.Coordinate) map[h.Coordinate]int {
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partNums := make(map[h.Coordinate]int)
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for _, chk := range []h.Coordinate{
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c.North(),
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c.NE(),
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c.East(),
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c.SE(),
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c.South(),
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c.SW(),
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c.West(),
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c.NW(),
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} {
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if m.Get(chk) >= '0' && m.Get(chk) <= '9' {
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v, pos := parseNumAt(m, chk)
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partNums[pos] = v
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}
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}
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return partNums
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}
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// parseNumAt returns the number at c and the Coordinate
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// that the first digit of that number is at
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func parseNumAt(m h.CoordByteMap, c h.Coordinate) (int, h.Coordinate) {
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var resStr string
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startCoord := c
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// From 'c' move left until we find the first digit
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chk := m.Get(startCoord)
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for coordIsNum(m, startCoord) {
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startCoord = startCoord.West()
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chk = m.Get(startCoord)
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}
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startCoord = startCoord.East()
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// Now put the number at 'startCoord' together
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parseNum := startCoord
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chk = m.Get(startCoord)
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for coordIsNum(m, parseNum) {
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resStr = fmt.Sprintf("%s%s", resStr, string(chk))
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parseNum = parseNum.East()
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chk = m.Get(parseNum)
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}
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if resStr == "" {
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return -1, h.Coordinate{X: -1, Y: -1}
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}
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return h.Atoi(resStr), startCoord
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}
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func coordIsNum(m h.CoordByteMap, c h.Coordinate) bool {
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wrk := m.Get(c)
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return wrk >= '0' && wrk <= '9'
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}
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