add day 10

day10/scores.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+    "os"
+    "fmt"
+    "strconv"
+    "strings"
+)
+
+// data types
+type Path struct {
+    start_x int
+    start_y int
+    end_x int
+    end_y int
+}
+
+// general util
+func check(e error) {
+    if e != nil { panic(e) }
+}
+
+func get_next_steps(field [][]byte, path *Path) []Path {
+    paths := make([]Path, 0, 4)
+    x := path.end_x
+    y := path.end_y
+    val := field[y][x]
+    
+    if y < len(field) - 1 {
+        down := field[y + 1][x]
+        if down == val + 1 {
+            paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x, end_y: y + 1 })
+        }
+    }
+    if y > 0 {
+        up := field[y - 1][x]
+        if up == val + 1 {
+            paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x, end_y: y - 1 })
+        }
+    }
+    if x < len(field[0]) - 1 {
+        right := field[y][x + 1]
+        if right == val + 1 {
+            paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x + 1, end_y: y })
+        }
+    }
+    if x > 0 {
+        left := field[y][x - 1]
+        if left == val + 1 {
+            paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x - 1, end_y: y })
+        }
+    }
+    return paths
+}
+
+func get_all_paths(field [][]byte) []Path {
+    paths := make([]Path, 0)
+    
+    // init
+    for _y, line := range field {
+        for _x, val := range line {
+            if val == 0 {
+                paths = append(paths, Path{start_x: _x, end_x: _x, start_y: _y, end_y: _y})
+            }
+        }
+    }
+    
+    // step by step
+    for i := 0; i < 9; i++ {
+        new_paths := make([]Path, 0, len(paths))
+        for _, path := range paths {
+            new_paths = append(new_paths, get_next_steps(field, &path)...)
+        }
+        paths = new_paths
+    }
+    
+    return paths
+}
+
+
+// main loop
+func main() {
+
+    // read in file
+    dat, err := os.ReadFile("data.txt")
+    check(err)
+    dat_str := strings.TrimSpace(string(dat))
+    
+    // contruct input as byte matrix 
+    lines := strings.Split(dat_str, "\n")
+    input := make([][]byte, 0, len(lines))
+    for _, line := range lines {
+        matrix_line := make([]byte, 0, len(line))
+        for _, char := range []rune(line) {
+            num, err := strconv.Atoi(string(char))
+            check(err)
+            matrix_line = append(matrix_line, byte(num))
+        }
+        input = append(input, matrix_line)
+    }
+
+    // calc scores
+    m := make(map[Path]bool)
+    for _, path := range get_all_paths(input) {
+        m[path] = true
+    }
+    fmt.Println(len(m))
+
+}