154 lines
2.7 KiB
Go
154 lines
2.7 KiB
Go
package main
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import (
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"bufio"
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"fmt"
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"os"
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"strconv"
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"time"
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)
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func main() {
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start := time.Now()
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partOne()
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duration := time.Since(start)
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partTwo()
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duration2 := time.Since(start)
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fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
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}
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func makeScanner(test bool) *bufio.Scanner {
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var f *os.File
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if test {
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f, _ = os.Open("inputs/testinput")
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} else {
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f, _ = os.Open("inputs/input")
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}
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reader := bufio.NewReader(f)
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return bufio.NewScanner(reader)
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}
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func mustAtoi(line []byte) int {
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i, err := strconv.Atoi(string(line))
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if err != nil {
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panic(err)
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}
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return i
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}
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type point struct {
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x int
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y int
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}
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type grid struct {
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m [][]int
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}
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func (g *grid) AddLine(start, end point, includeHorizontal bool) {
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for _, p := range LineFromPoints(start, end, includeHorizontal) {
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if g.m[p.x] == nil {
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g.m[p.x] = make([]int, 1000)
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}
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g.m[p.x][p.y]++
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}
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}
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func LineFromPoints(start, end point, includeHorizontal bool) []point {
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if start.x != end.x && start.y != end.y && !includeHorizontal {
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return []point{}
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}
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var xstep, ystep int
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if start.x > end.x {
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xstep = -1
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}
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if start.x < end.x {
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xstep = 1
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}
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if start.y > end.y {
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ystep = -1
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}
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if start.y < end.y {
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ystep = 1
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}
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points := []point{}
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for i, j := start.x, start.y; i != end.x+xstep || j != end.y+ystep; i, j = i+xstep, j+ystep {
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points = append(points, point{x: i, y: j})
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}
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return points
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}
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func parsePoints(line string) (point, point) {
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var start, end point
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var num []byte // accumulator
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var state int // parser state: 0: x1 1: y1 2: x2 3: y2
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for i := 0; i < len(line); i++ {
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switch line[i] {
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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num = append(num, line[i])
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case ' ':
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start.y = mustAtoi(num)
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num = []byte{}
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i += 3 // jump past '-> '
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state = 2
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case ',':
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if state == 0 {
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start.x = mustAtoi(num)
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num = []byte{}
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state = 1
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}
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if state == 2 {
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end.x = mustAtoi(num)
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num = []byte{}
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state = 3
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}
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}
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}
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end.y = mustAtoi(num)
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return start, end
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}
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func partOne() {
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scanner := makeScanner(false)
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grid := &grid{
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m: make([][]int, 1000),
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}
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for scanner.Scan() {
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line := scanner.Text()
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start, end := parsePoints(line)
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grid.AddLine(start, end, false)
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}
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var danger int
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for i := range grid.m {
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for j := range grid.m[i] {
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if grid.m[i][j] > 1 {
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danger++
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}
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}
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}
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fmt.Println(danger)
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}
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func partTwo() {
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scanner := makeScanner(false)
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grid := &grid{
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m: make([][]int, 1000),
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}
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for scanner.Scan() {
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line := scanner.Text()
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start, end := parsePoints(line)
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grid.AddLine(start, end, true)
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}
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var danger int
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for i := range grid.m {
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for j := range grid.m[i] {
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if grid.m[i][j] > 1 {
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danger++
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}
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}
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}
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fmt.Println(danger)
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}
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