2022 Days 12 & 13 Complete!

2022/day12/main.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"fmt"
+	"math"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	m := h.StringSliceToCoordByteMap(inp)
+	start, _ := m.FindFirst('S')
+	m.Put(start, 'a')
+	end, _ := m.FindFirst('E')
+	m.Put(end, 'z')
+
+	fmt.Println("# Part 1")
+	fmt.Println("Steps:", bfs(m, start, end))
+}
+
+func part2(inp []string) {
+	m := h.StringSliceToCoordByteMap(inp)
+	starts := m.FindAll('a')
+	if s, err := m.FindFirst('S'); err == nil {
+		m.Put(s, 'a')
+		starts = append(starts, s)
+	}
+	end, _ := m.FindFirst('E')
+	m.Put(end, 'z')
+
+	minSteps := math.MaxInt
+	for _, start := range starts {
+		curSteps := bfs(m, start, end)
+		if minSteps > curSteps {
+			minSteps = curSteps
+		}
+	}
+	fmt.Println("# Part 2")
+	fmt.Println("Steps:", minSteps)
+}
+
+func bfs(m h.CoordByteMap, start, end h.Coordinate) int {
+	seen := make(map[h.Coordinate]bool)
+	seen[start] = true
+	queue := []h.Coordinate{start}
+	steps := 0
+	found := false
+	// BFS Search
+SEARCH:
+	for len(queue) > 0 {
+		k := len(queue)
+		for i := 0; i < k; i++ {
+			curr := queue[0]
+			currVal := m.Get(curr)
+			queue = queue[1:]
+			if end.Equals(curr) {
+				found = true
+				break SEARCH
+			}
+			for _, dir := range curr.GetOrthNeighbors() {
+				if !m.ContainsCoord(dir) || seen[dir] {
+					continue
+				}
+				newVal := m.Get(dir)
+				greater := m.Get(dir) > currVal
+				if greater && newVal-currVal > 1 {
+					continue
+				}
+				seen[dir] = true
+				queue = append(queue, dir)
+			}
+		}
+		steps++
+	}
+	if !found {
+		//fmt.Println("Path from", start, "to", end, "not found!")
+		return math.MaxInt
+	}
+	return steps
+}