day 10

Author: BrianBrenner

10/input.txt

@@ -0,0 +1,45 @@
+676781023010121078756541010565410126589652103
+787692014523134569687238921076321087676543012
+896543210674013278798107831089980896567122107
+654100134985329143237356540123678925498033498
+783210325676438050123445443294541012321044589
+694309018984567267034576356789032008769655678
+345678567823432178125689219878102109678724369
+456969430214563089068701008765210234569013212
+327854321005478873879010123674377654354321001
+218901232876569912968123294589988912210132432
+107650343985567803451054387487676903432101561
+210545674783498712589965236596567876543650170
+323432185692105605678876145645430967858743289
+214981092185434104987986001034321458969801001
+105670123076393213098887632125010321578932102
+789889874101284332106798540136521230432840013
+876776965692379876087034567287650145521051224
+965460150789561045696129898398010676670569345
+234321041276432038765408765498723487989678496
+165432132345987129932317454389654395432310987
+074540122187656087801326761230101276211001236
+783458043090345196540410890121210989303456545
+892169834901210105432589789032367893456327896
+701078985810012234501678776543456302587410187
+667654856798943107657578905494543211693217896
+578983012367874038748765412387687600784506787
+457832343455465129889854307898990521099615690
+300761567854321012934781212387121434988794321
+211650434969482103245690101236012345670188760
+672349123478091014132386789845621012873279454
+589678012562182365001675632736790123964560303
+432547001601276478976543541345887654456781212
+321232118762345569885012310212994569323998800
+210321129098710378894322343200123478010878901
+300410030123601256765011056123430765430765432
+321567542034510349810782987001521894321045645
+434788601945654878725693965432676541013236012
+095699717898783965434344876501987034901107823
+187659826500192854303239884567698127872787934
+234549834410201601214138793298012016543396543
+067812765325360519871025682105623456671230123
+154908901876451456789014871234702965580145674
+233217010945962359874323960189811874495432985
+945606321034876543265221054076320432356781876
+876545432321089012100100123165410321065690165

10/main.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// finishes uses the coords as a key, ie "r,c" ex: "1,3". if
+func dfs(grid [][]int, r int, c int, prev int, finishes *map[string]bool) {
+	if r < 0 || r >= len(grid) || c < 0 || c >= len(grid[0]) {
+		return
+	}
+	if grid[r][c] != prev+1 {
+		return
+	}
+	if grid[r][c] == 9 {
+		coordKey := strconv.Itoa(r) + "," + strconv.Itoa(c)
+		(*finishes)[coordKey] = true
+	}
+	dfs(grid, r-1, c, grid[r][c], finishes)
+	dfs(grid, r+1, c, grid[r][c], finishes)
+	dfs(grid, r, c+1, grid[r][c], finishes)
+	dfs(grid, r, c-1, grid[r][c], finishes)
+}
+
+func dfs2(grid [][]int, r int, c int, prev int) int {
+	if r < 0 || r >= len(grid) || c < 0 || c >= len(grid[0]) {
+		return 0
+	}
+	if grid[r][c] != prev+1 {
+		return 0
+	}
+	if grid[r][c] == 9 {
+		return 1
+	}
+	return dfs2(grid, r-1, c, grid[r][c]) + dfs2(grid, r+1, c, grid[r][c]) + dfs2(grid, r, c+1, grid[r][c]) + dfs2(grid, r, c-1, grid[r][c])
+}
+
+func part1() {
+	//raw, _ := os.ReadFile("test.txt")
+	raw, _ := os.ReadFile("input.txt")
+	data := string(raw)
+	grid := [][]int{}
+	for _, line := range strings.Split(data, "\n") {
+		row := []int{}
+		for _, char := range line {
+			num, _ := strconv.Atoi(string(char))
+			row = append(row, num)
+		}
+		grid = append(grid, row)
+	}
+
+	tot := 0
+	for r := range len(grid) {
+		for c := range len(grid[0]) {
+			if grid[r][c] == 0 {
+				finishes := map[string]bool{}
+				dfs(grid, r, c, -1, &finishes)
+				tot += len(finishes)
+			}
+		}
+	}
+	fmt.Println(tot)
+}
+
+func part2() {
+	//raw, _ := os.ReadFile("test.txt")
+	raw, _ := os.ReadFile("input.txt")
+	data := string(raw)
+	grid := [][]int{}
+	for _, line := range strings.Split(data, "\n") {
+		row := []int{}
+		for _, char := range line {
+			num, _ := strconv.Atoi(string(char))
+			row = append(row, num)
+		}
+		grid = append(grid, row)
+	}
+
+	tot := 0
+	for r := range len(grid) {
+		for c := range len(grid[0]) {
+			if grid[r][c] == 0 {
+				tot += dfs2(grid, r, c, -1)
+			}
+		}
+	}
+	fmt.Println(tot)
+}
+
+func main() {
+	part1()
+	part2()
+}

10/test.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732