much better day13 after looking at others

2022/go/day12/day12.go

@@ -0,0 +1,103 @@
+package day12
+
+import (
+	"fmt"
+	"strings"
+	"adventofcode2022/utils"
+	"adventofcode2022/utils/grid2d"
+)
+
+type cell struct {
+	height   int
+	distance int
+}
+
+type coord struct {
+	x int
+	y int
+}
+
+func Part1(input string) int {
+	startCoord, grid := parseInput(input)
+	fillGrid(grid)
+	printGrid(grid)
+	c := grid.Get(startCoord.x, startCoord.y)
+	return c.distance
+}
+
+func Part2(input string) int {
+	_, grid := parseInput(input)
+	fillGrid(grid)
+	min := utils.MaxInt
+	for j := 0; j < grid.SizeY(); j++ {
+		for i := 0; i < grid.SizeX(); i++ {
+			c1 := grid.Get(i, j)
+			if c1.height == 0 {
+				min = utils.Min(min, c1.distance)
+			}
+		}
+	}
+	return min
+}
+
+func parseInput(input string) (coord, *grid2d.Grid[*cell]) {
+	lines := strings.Split(input, "\n")
+	grid := grid2d.NewGrid[*cell](len(lines[0]), len(lines), nil)
+	startCoord := coord{-1, -1}
+	for j, line := range lines {
+		for i, c := range line {
+			newCell := &cell{height: int(c - 'a'), distance: utils.MaxInt}
+			if c == 'S' {
+				newCell.height = 0
+				startCoord.x = i
+				startCoord.y = j
+			} else if c == 'E' {
+				newCell.height = 25
+				newCell.distance = 0
+			}
+			grid.Set(i, j, newCell)
+		}
+	}
+	return startCoord, grid
+}
+
+func fillGrid(grid *grid2d.Grid[*cell]) {
+	done := false
+	for !done {
+		done = true
+		for j := 0; j < grid.SizeY(); j++ {
+			for i := 0; i < grid.SizeX(); i++ {
+				c1 := grid.Get(i, j)
+				if c1.distance == utils.MaxInt {
+					continue
+				}
+				moves := [][]int{{0, 1}, {0, -1}, {1, 0}, {-1, 0}}
+				for _, move := range moves {
+					x2 := i + move[0]
+					y2 := j + move[1]
+					c2 := grid.Get(x2, y2)
+					if c2 == nil {
+						continue
+					}
+					if c2.height < c1.height-1 {
+						continue
+					}
+					if c2.distance > c1.distance+1 {
+						c2.distance = c1.distance + 1
+						done = false
+					}
+				}
+			}
+		}
+	}
+}
+
+func printGrid(grid *grid2d.Grid[*cell]) {
+	r := grid.StringWithFormatter(func(c *cell, i, j int) string {
+		if c.distance == utils.MaxInt {
+			return "?? "
+		}
+		return fmt.Sprintf("%02d ", c.distance)
+	})
+	fmt.Println(r)
+}