2024.10

Author: jerodev

2024/10-map/example.txt

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

2024/10-map/input.txt

@@ -0,0 +1,52 @@
+0145677654325490845691012345621876560340100123012398
+1238988998216781932782121234010983401259230034563387
+4323589867205432801543210945125672378768341459654456
+1014678454102301765456901876034561769897652368776301
+6765521543201512350307872962120120850785677879789210
+0896430439810487461217965871298438941454980968654321
+1765012126723596543478014560167569032363211457256762
+2872121035434654302569123441455678121071102340145895
+3961230345985783211098710332334599432980098743232434
+4550145456676890100167000146721087641001217650141325
+9649056765489910651254121035890014550732309654210016
+8738769894676328762343236124301123669845498763227807
+7129787923565439651456347833210008778996787120156998
+1013496014567010340987656944782119211087898031343210
+1012345002198321232876501855693024302332196541034101
+1234567123023450901965432761054435678445087670123256
+0144898454910767845670301622169546589556764581214347
+4343732367867893034981243213678696765698873294309838
+1234351078754702121893214504589787894780987101456789
+0943765469843213210721303698921009683211074560167678
+7856874348765434785630410787652118701202983076298987
+6765989219210125698540521236543025654343892189347567
+5667867804321087582101638347432134509856782345456498
+1054876965691296443492789858901213212790101276012387
+2123965476780125356783498767654300103685230983401456
+3278954587821034219870567658967876234576541092560845
+2567543296930761006721498743478965987655612451076921
+1056230145945852345012345412661234554567803367987830
+2340167034876945123211296401780109693069954298756101
+7887658123985231034500787345691218782178769110343232
+6992349032100112985011216217885011071078978021232349
+5801239844301101676720105606976522362567987876541458
+4321023765432432369838234745983439453454376965430167
+3087610321396565458949549836112378321043105302301298
+2198565410187076327658678921001065439652234211017657
+3233478903216189014547664567632104508701230322928943
+4542369894103273223014523498549812012349821498834012
+7651423765764784132123210210038763676256734567765423
+8960314349845695041012396342121054985109875498656701
+4871005256736786780169487653434873014018766787567892
+5654196149821677893278565694565963223321051096450943
+6743287032120563034567684787696954101438142345321056
+7899180129061432125675893256787845698589233239885469
+3458098938778743210986710143876034787670132178596378
+2167347845609654331235430782932128236101056017687267
+6056256741012103220543521691047659145692347012570167
+7890165432343210110652434598798578036785498743456898
+6784567876758701328701223123623457629876901234347107
+5413218965869232499899810034510256510267892301298256
+4303409954978149581234745218760105100126765410789340
+3212567823019058670365634309451234981237898323870121
+4321016012108767621256565678321015676546767654965432

2024/10-map/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"advent-of-code/util"
+	"bufio"
+	"fmt"
+)
+
+var grid [][]byte
+
+func main() {
+	file := util.FileFromArgs()
+	scan := bufio.NewScanner(file)
+
+	var starts []position
+
+	for scan.Scan() {
+		row := scan.Bytes()
+
+		for i := range row {
+			row[i] = row[i] - '0'
+
+			if row[i] == 0 {
+				starts = append(starts, position{i, len(grid)})
+			}
+		}
+
+		grid = append(grid, row)
+	}
+
+	var trials, trialPoints int
+	for i := range starts {
+		trialheads := walkUp(starts[i])
+		trials += len(util.Unique(trialheads))
+		trialPoints += len(trialheads)
+	}
+
+	fmt.Println(trials)
+	fmt.Println(trialPoints)
+}
+
+type position struct {
+	X, Y int
+}
+
+// walkUp starts at a position and returns all sumits it can reach with a unique path
+func walkUp(p position) []position {
+	height := grid[p.Y][p.X]
+	if height == 9 {
+		return []position{p}
+	}
+
+	var summits []position
+	if p.X > 0 && grid[p.Y][p.X-1] == height+1 { // LEFT
+		summits = append(summits, walkUp(position{p.X - 1, p.Y})...)
+	}
+	if p.X < len(grid[0])-1 && grid[p.Y][p.X+1] == height+1 { // RIGHT
+		summits = append(summits, walkUp(position{p.X + 1, p.Y})...)
+	}
+	if p.Y > 0 && grid[p.Y-1][p.X] == height+1 { // UP
+		summits = append(summits, walkUp(position{p.X, p.Y - 1})...)
+	}
+	if p.Y < len(grid)-1 && grid[p.Y+1][p.X] == height+1 { // DOWN
+		summits = append(summits, walkUp(position{p.X, p.Y + 1})...)
+	}
+
+	return summits
+}

util/slices.go

@@ -10,3 +10,26 @@ func CountOccurrences[V comparable](s []V, value V) int {
 
 	return count
 }
+
+// Unique returns a new slice with only unique values
+func Unique[V comparable](s []V) []V {
+	ns := make([]V, 0, len(s))
+
+	var duplicate bool
+	for i := range s {
+		duplicate = false
+
+		for j := range ns {
+			if s[i] == ns[j] {
+				duplicate = true
+				break
+			}
+		}
+
+		if !duplicate {
+			ns = append(ns, s[i])
+		}
+	}
+
+	return ns
+}

util/slices_test.go

@@ -0,0 +1,11 @@
+package util
+
+import "testing"
+
+func TestUnique(t *testing.T) {
+	s := Unique([]int{1, 2, 3, 1, 2, 3})
+
+	if len(s) != 3 || s[0] != 1 || s[1] != 2 || s[2] != 3 {
+		t.Error("Expected unique array, got ", s)
+	}
+}