131 lines
2.6 KiB
Go
131 lines
2.6 KiB
Go
package d5
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import (
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"math"
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"strconv"
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"strings"
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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 segment struct {
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a point
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b point
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}
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func createSegments(lines []string) []segment {
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segments := make([]segment, len(lines))
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for i, line := range lines {
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points := strings.Split(line, " -> ")
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start := strings.Split(points[0], ",")
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end := strings.Split(points[1], ",")
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x1, _ := strconv.Atoi(start[0])
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y1, _ := strconv.Atoi(start[1])
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x2, _ := strconv.Atoi(end[0])
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y2, _ := strconv.Atoi(end[1])
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segments[i] = segment{point{x1, y1}, point{x2, y2}}
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}
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return segments
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}
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func generatePoints(segments []segment) []point {
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points := []point{}
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for _, segment := range segments {
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if segment.a.x == segment.b.x {
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min := int(math.Min(float64(segment.a.y), float64(segment.b.y)))
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max := int(math.Max(float64(segment.a.y), float64(segment.b.y)))
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for i := min; i <= max; i++ {
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points = append(points, point{segment.a.x, i})
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}
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}
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if segment.a.y == segment.b.y {
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min := int(math.Min(float64(segment.a.x), float64(segment.b.x)))
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max := int(math.Max(float64(segment.a.x), float64(segment.b.x)))
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for i := min; i <= max; i++ {
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points = append(points, point{i, segment.a.y})
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}
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}
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}
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return points
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}
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func generatePointsWithDiagonals(segments []segment) []point {
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points := []point{}
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for _, segment := range segments {
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startX := segment.a.x
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startY := segment.a.y
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endX := segment.b.x
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endY := segment.b.y
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dx := 1
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dy := 1
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if segment.a.x == segment.b.x {
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dx = 0
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} else if segment.a.x > segment.b.x {
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dx = -1
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}
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if segment.a.y == segment.b.y {
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dy = 0
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} else if segment.a.y > segment.b.y {
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dy = -1
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}
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points = append(points, point{startX, startY})
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for startX != endX || startY != endY {
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startX += dx
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startY += dy
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points = append(points, point{startX, startY})
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}
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}
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return points
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}
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func findIntersections(points []point) map[point]int {
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intersections := map[point]int{}
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for _, a := range points {
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intersections[a]++
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}
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return intersections
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}
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func countIntersections(intersections map[point]int) int {
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count := 0
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for _, crosses := range intersections {
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if crosses > 1 {
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count++
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}
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}
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return count
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}
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func D5(input string) int {
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lines := strings.Split(strings.TrimSpace(input), "\n")
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segments := createSegments(lines)
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points := generatePoints(segments)
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intersections := findIntersections(points)
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return countIntersections(intersections)
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}
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func D5P2(input string) int {
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lines := strings.Split(strings.TrimSpace(input), "\n")
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segments := createSegments(lines)
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points := generatePointsWithDiagonals(segments)
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intersections := findIntersections(points)
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return countIntersections(intersections)
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}
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