--- /dev/null
+
+package day5
+
+import (
+ "fmt"
+ "os"
+ "strconv"
+ "io"
+ "bufio"
+ "strings"
+)
+
+type Matrix struct {
+ data [][]int
+ rows, cols int
+}
+
+func (m *Matrix) addRows(r int) {
+ if r <= 0 { return }
+
+ m.rows += r
+ if m.cols == 0 { return }
+
+ for i := 0; i < r; i++ {
+ fill := make([]int, m.cols)
+ m.data = append(m.data, fill)
+ }
+}
+
+func (m *Matrix) addCols(c int) {
+ if c <= 0 { return }
+
+ m.cols += c
+ if m.rows == 0 { return }
+
+ fill := make([]int, c)
+ for y := 0; y < m.rows; y++ {
+ m.data[y] = append(m.data[y], fill...)
+ }
+}
+
+func (m *Matrix) hasPoint(p Point) {
+ //fmt.Printf("Matrix\n%v\nhas point %v?\n", m, p)
+ if p.x >= m.cols {
+ m.addCols(p.x + 1 - m.cols)
+ }
+ if p.y >= m.rows {
+ m.addRows(p.y + 1 - m.rows)
+ }
+ //fmt.Printf("Resulting matrix\n%v\n", m)
+}
+
+func (m Matrix) String() (s string) {
+ for y := 0; y < m.rows; y++ {
+ s += "\n"
+ for x := 0; x < m.cols; x++ {
+ v := m.data[y][x]
+ if v == 0 {
+ s += "."
+ } else {
+ s += strconv.Itoa(v)
+ }
+ }
+ }
+ return
+}
+
+type Point struct {
+ x, y int
+}
+
+type Line struct {
+ start, end Point
+}
+
+func readInput(r io.Reader) (lines []Line, err error) {
+ s := bufio.NewScanner(r)
+
+ lines = make([]Line, 0, 12)
+ for s.Scan() {
+ ws := strings.Split(s.Text(), " ")
+ ls := strings.Split(ws[0], ",")
+ rs := strings.Split(ws[2], ",")
+ x1, err := strconv.Atoi(ls[0])
+ if err != nil { return nil, err }
+ y1, err := strconv.Atoi(ls[1])
+ if err != nil { return nil, err }
+ x2, err := strconv.Atoi(rs[0])
+ if err != nil { return nil, err }
+ y2, err := strconv.Atoi(rs[1])
+ if err != nil { return nil, err }
+
+ p := Line {start: Point{x1, y1}, end: Point{x2, y2}}
+ lines = append(lines, p)
+ }
+ return lines, err
+}
+
+func max(x, y int) (v int){
+ v = x
+ if x < y { v = y }
+ return
+}
+
+func min(x, y int) (v int){
+ v = x
+ if x > y { v = y }
+ return
+}
+
+func (m *Matrix) drawLines(lines []Line) {
+ for _, l := range lines {
+ if l.start.x == l.end.x {
+ //fmt.Printf("Draw vertical line %v on\n%v\n", l, m)
+
+ m.hasPoint(l.start)
+ m.hasPoint(l.end)
+
+ x := l.start.x
+ y := min(l.start.y, l.end.y)
+ for ; y <= max(l.start.y, l.end.y); y++ {
+ //fmt.Printf("draw [%v][%v]\n", x, y)
+ m.data[y][x]++
+ //fmt.Printf("Matrix\n%v\n", m)
+ }
+ //fmt.Printf("Drawn \n%v\n", m)
+ } else if l.start.y == l.end.y {
+ //fmt.Printf("Draw horizontal line %v on\n%v\n", l, m)
+
+ m.hasPoint(l.start)
+ m.hasPoint(l.end)
+
+ x := min(l.start.x, l.end.x)
+ y := l.start.y
+ for ; x <= max(l.start.x, l.end.x); x++ {
+ m.data[y][x]++
+ }
+ }
+ }
+}
+
+func f1(lines []Line) (count int) {
+ var m Matrix
+
+ m.drawLines(lines)
+ for y := 0; y < m.rows; y++ {
+ for x := 0; x < m.cols; x++ {
+ if m.data[y][x] > 1 { count++ }
+ }
+ }
+ return count
+}
+
+func RunF1(input string) {
+ h0, err := os.Open(input)
+ if err != nil { return }
+ defer h0.Close()
+
+ /*
+ var n Matrix
+ //n.hasPoint(Point{2, 2})
+ fmt.Printf("%v\n", n)
+ n.addCols(3)
+ n.addRows(3)
+ fmt.Printf("%v\n", n)
+ n.data[0][0] = 1
+ n.data[0][1] = 2
+ n.data[0][2] = 3
+ n.data[1][0] = 4
+ n.data[1][1] = 5
+ n.data[1][2] = 6
+ n.data[2][0] = 7
+ n.data[2][1] = 8
+ n.data[2][2] = 9
+ fmt.Printf("%v\n", n)
+ */
+
+ ls, err := readInput(h0)
+ fmt.Printf("Input %v\n", ls)
+
+ var m Matrix
+ m.drawLines(ls)
+ count := f1(ls)
+ //fmt.Printf("Matrix %v\n", m)
+ fmt.Printf("Answer1: %v\n", count)
+}
+
projects / aoc-2021.git / commitdiff