Day 17: part 1

day17/day17.go

@@ -0,0 +1,130 @@
+package day17
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+type PQ struct {
+	queue [][6]int
+}
+
+func (pq *PQ) len() int {
+	return len((*pq).queue)
+}
+func (pq *PQ) pop() (int, int, int, int, int, int) {
+	pq.sort()
+	r := (*pq).queue[0]
+	(*pq).queue = (*pq).queue[1:]
+
+	return r[0], r[1], r[2], r[3], r[4], r[5]
+}
+func (pq *PQ) push(path [6]int) {
+	(*pq).queue = append((*pq).queue, path)
+}
+func (pq *PQ) sort() {
+	slices.SortFunc((*pq).queue, func(a, b [6]int) int {
+		if a[0] > b[0] {
+			return 1
+		} else if a[0] < b[0] {
+			return -1
+		} else {
+			return 0
+		}
+	})
+}
+
+func Solution1(filepath string) int {
+	m := readInput(filepath)
+
+	pq := PQ{}
+	seen := make(map[string]bool)
+	pq.push([6]int{0, 0, 0, 0, 0, 0}) // heat loss, y, x, dY, dX, n of steps in straight line
+
+	for pq.len() > 0 {
+		heatLoss, y, x, dY, dX, n := pq.pop()
+		if y == len(m)-1 && x == len(m[y])-1 {
+			return heatLoss
+		}
+
+		seenKey := fmt.Sprintf("%d;%d;%d;%d;%d", y, x, dY, dX, n)
+		if seen[seenKey] {
+			continue
+		}
+		seen[seenKey] = true
+
+		// keep going in the same direction
+		if n < 3 && [2]int{dY, dX} != [2]int{0, 0} {
+			newY, newX := y+dY, x+dX
+			if newY < 0 || newY >= len(m) || newX < 0 || newX >= len(m[0]) {
+				// do nothing, I don't want to invert this condition
+			} else {
+				pq.push([6]int{heatLoss + m[newY][newX], newY, newX, dY, dX, n + 1})
+			}
+		}
+
+		// explore all the other directions except for the current and its reverse
+		for _, diffs := range [][2]int{{0, 1}, {0, -1}, {1, 0}, {-1, 0}} {
+			newDY, newDX := diffs[0], diffs[1]
+			newY, newX := y+newDY, x+newDX
+			if newDir := [2]int{newDY, newDX}; newDir == [2]int{dY, dX} || newDir == [2]int{-dY, -dX} {
+				continue
+			}
+			if newY < 0 || newY >= len(m) || newX < 0 || newX >= len(m[newY]) {
+				continue
+			}
+			pq.push([6]int{heatLoss + m[newY][newX], newY, newX, newDY, newDX, 1})
+		}
+
+	}
+	return -1
+}
+
+func Solution2(filepath string) int {
+	return -1
+}
+
+func readInput(filepath string) [][]int {
+	file, err := os.Open(filepath)
+	if err != nil {
+		log.Fatalf("Failed to open the input file with: %v\n", err.Error())
+	}
+
+	var matrix [][]int
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		currentRow := strings.Split(scanner.Text(), "")
+		currentRowNums := make([]int, len(currentRow))
+		for i, el := range currentRow {
+			currentRowNums[i] = parseInt(el)
+		}
+		matrix = append(matrix, currentRowNums)
+	}
+	if err = scanner.Err(); err != nil {
+		log.Fatalf("Error during input file read: %v\n", err.Error())
+	}
+
+	return matrix
+}
+
+func parseInt(s string) int {
+	num, err := strconv.ParseInt(s, 10, 64)
+	if err != nil {
+		log.Fatalf("Failed to parse number %v with: %s\n", s, err.Error())
+	}
+
+	return int(num)
+}
+
+func printMatrix(m [][]int) {
+	fmt.Println("-----MATRIX START-----")
+	for _, row := range m {
+		fmt.Println(row)
+	}
+	fmt.Println("------MATRIX END------")
+}

day17/day17_test.go

@@ -0,0 +1,55 @@
+package day17
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestSolution1(t *testing.T) {
+	cases := map[string]int{
+		"test_input11": 102,
+	}
+
+	for input, expectedResult := range cases {
+		result := Solution1(input)
+
+		assert.Equal(t, result, expectedResult, "Solution1()")
+	}
+}
+
+func TestSolution2(t *testing.T) {
+	cases := map[string]int{
+		"test_input11": 0,
+	}
+
+	for input, expectedResult := range cases {
+		result := Solution2(input)
+
+		assert.Equal(t, result, expectedResult, "Solution2()")
+	}
+}
+
+func TestPriorityQueue(t *testing.T) {
+	pq := PQ{}
+	pq.push([6]int{0, 0, 0, 0, 0, 0})
+	pq.push([6]int{4, 0, 0, 0, 0, 0})
+	pq.push([6]int{2, 0, 0, 0, 0, 0})
+	pq.push([6]int{6, 0, 0, 0, 0, 0})
+	pq.push([6]int{99, 0, 0, 0, 0, 0})
+	pq.push([6]int{1, 0, 0, 0, 0, 0})
+
+	cases := map[int]int{
+		0: 0,
+		1: 1,
+		2: 2,
+		3: 4,
+		4: 6,
+		5: 99,
+	}
+
+	for i := 0; i <= 5; i++ {
+		hl, _, _, _, _, _ := pq.pop()
+		assert.Equal(t, cases[i], hl, "PQ push(), pop()")
+	}
+	assert.Equal(t, 0, pq.len(), "PQ len()")
+}

day17/test_input11

@@ -0,0 +1,13 @@
+2413432311323
+3215453535623
+3255245654254
+3446585845452
+4546657867536
+1438598798454
+4457876987766
+3637877979653
+4654967986887
+4564679986453
+1224686865563
+2546548887735
+4322674655533

go.mod

@@ -1,3 +1,11 @@
 module advent-of-code
 
 go 1.23.2
+
+require github.com/stretchr/testify v1.9.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -17,6 +17,7 @@ import (
 	"advent-of-code/day14"
 	"advent-of-code/day15"
 	"advent-of-code/day16"
+	"advent-of-code/day17"
 	"fmt"
 	"time"
 )
@@ -76,4 +77,7 @@ func main() {
 
 	runSolution(16, 1, func() int { return day16.Solution1("inputs/day16") })
 	runSolution(16, 2, func() int { return day16.Solution2("inputs/day16") })
+
+	runSolution(17, 1, func() int { return day17.Solution1("inputs/day17") })
+	runSolution(17, 2, func() int { return day17.Solution2("inputs/day17") })
 }