add day14

day14/safetyfactor.go

@@ -0,0 +1,87 @@
+package main
+
+import ("os"; "strings"; "fmt"; "strconv"; "regexp")
+
+type Board struct {
+    width uint8
+    height uint8
+}
+
+type Robot struct {
+    x uint8
+    y uint8
+    vx int8
+    vy int8
+}
+
+func (r Robot) Step(b Board, n uint) Robot {
+    pos_vx := int(r.vx)
+    pos_vy := int(r.vy)
+    if pos_vx < 0 { pos_vx = int(b.width)  + pos_vx }
+    if pos_vy < 0 { pos_vy = int(b.height) + pos_vy }
+
+    new_x := uint( uint(r.x) + uint(pos_vx) * n ) % uint(b.width)
+    new_y := uint( uint(r.y) + uint(pos_vy) * n ) % uint(b.height)
+    
+    return Robot{uint8(new_x), uint8(new_y), r.vx, r.vy}
+}
+
+func check(e error) {
+    if e != nil {
+        panic(e)
+    }
+}
+
+func abs(n int) uint {
+    if n < 0 { return uint(-n) }
+    return uint(n)
+}
+
+func NewRobot(line string) Robot {
+    pattern := regexp.MustCompile(`-?\d+`)
+    matches := pattern.FindAllString(line, -1)
+    numbers := [4]int{}
+
+    for i, match := range matches {
+        num, err := strconv.Atoi(match)
+        check(err)
+        numbers[i] = num
+    }
+
+    return Robot{uint8(numbers[0]), uint8(numbers[1]), int8(numbers[2]), int8(numbers[3])}
+} 
+
+func main() {
+    dat, err := os.ReadFile("data.txt")
+    check(err)
+    
+    lines := strings.Split(strings.TrimSpace(string(dat)), "\n")
+    
+    board := Board{101, 103}
+    robots := make([]Robot, 0, 100)
+
+    for _, line := range lines {
+        robots = append(robots, NewRobot(line))
+    }
+    
+    // run simulation
+    for i := range robots {
+        robots[i] = robots[i].Step(board, 100)
+    }
+
+    // count in quadrants
+    q1, q2, q3, q4 := 0, 0, 0, 0
+    
+    for _, r := range robots {
+        switch {
+            case r.x < (board.width / 2) && r.y < (board.height / 2): q1++
+            case r.x > (board.width / 2) && r.y < (board.height / 2): q2++
+            case r.x < (board.width / 2) && r.y > (board.height / 2): q3++
+            case r.x > (board.width / 2) && r.y > (board.height / 2): q4++
+        } 
+    }
+
+    fmt.Println(q1, q2, q3, q4)
+    fmt.Println(q1 * q2 * q3 * q4)
+}
+