115 lines
2.5 KiB
Go
115 lines
2.5 KiB
Go
package main
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import (
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"fmt"
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"math"
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"os"
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"strings"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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var part = -1
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var testRow = 2000000
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var watch bool
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var watchRows = 1
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func main() {
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inp := h.StdinToStringSlice()
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if len(os.Args) > 1 {
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for _, arg := range os.Args[1:] {
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if strings.HasPrefix(arg, "--part") || strings.HasPrefix(arg, "-p") {
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if strings.Contains(arg, "=") {
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pts := strings.Split(arg, "=")
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part = h.Atoi(pts[1])
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}
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} else if strings.HasPrefix(arg, "--row") || strings.HasPrefix(arg, "-r") {
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if strings.Contains(arg, "=") {
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pts := strings.Split(arg, "=")
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testRow = h.Atoi(pts[1])
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}
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} else if strings.HasPrefix(arg, "--watch") || strings.HasPrefix(arg, "-w") {
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watch = true
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if strings.Contains(arg, "=") {
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pts := strings.Split(arg, "=")
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if pts[1] == "full" {
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watchRows = -1
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} else {
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watchRows = h.Atoi(pts[1])
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}
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}
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}
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}
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}
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if part == 1 || part == -1 {
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part1(inp)
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}
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if part == 2 || part == -1 {
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part2(inp)
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}
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}
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func part1(inp []string) {
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min_x, max_x := math.MaxInt, math.MinInt
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var spots [][]int
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for i := range inp {
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s, b := strToCoords(inp[i])
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xs, ys, xb, yb := s.X, s.Y, b.X, b.Y
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dist := s.Distance(b)
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l, r := xs-dist, xs+dist
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min_x = h.Min(min_x, l)
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max_x = h.Max(max_x, r)
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spots = append(spots, []int{xs, ys, xb, yb, dist})
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}
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var nopeCount int
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for x := min_x; x <= max_x; x++ {
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for _, c := range spots {
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if x == c[2] && testRow == c[3] {
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break
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}
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if h.ManhattanDistance(x, testRow, c[0], c[1]) <= c[4] {
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nopeCount++
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break
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}
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}
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}
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fmt.Println("# Part 1")
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fmt.Println(nopeCount)
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}
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func part2(inp []string) {
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var spots [][]int
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for i := range inp {
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s, b := strToCoords(inp[i])
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xs, ys, xb, yb := s.X, s.Y, b.X, b.Y
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dist := s.Distance(b)
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spots = append(spots, []int{xs, ys, xb, yb, dist})
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}
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min, max := 0, testRow*2
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// Brute-force it
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for y := min; y <= max; y++ {
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SEARCH:
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for x := min; x <= max; x++ {
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for _, c := range spots {
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if dx, dy := c[0]-x, c[1]-y; h.Abs(dx)+h.Abs(dy) <= c[4] {
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// Jump across the sensor's scan area
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x += c[4] - h.Abs(dy) + dx
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continue SEARCH
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}
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}
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// If we get here, we found it.
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fmt.Println("# Part 2")
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fmt.Println(x*4000000 + y)
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return
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}
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}
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}
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func strToCoords(s string) (h.Coordinate, h.Coordinate) {
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var sensor, beacon h.Coordinate
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r := strings.NewReader(s)
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fmt.Fscanf(r, "Sensor at x=%d, y=%d: closest beacon is at x=%d, y=%d", &sensor.X, &sensor.Y, &beacon.X, &beacon.Y)
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return sensor, beacon
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}
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