feat: completed day 6 for advent of code 2025

2025/cmd/root.go

@@ -14,6 +14,7 @@ import (
 	"cpatino.com/advent-of-code/2025/day03"
 	"cpatino.com/advent-of-code/2025/day04"
 	"cpatino.com/advent-of-code/2025/day05"
+	"cpatino.com/advent-of-code/2025/day06"
 )
 
 var days = map[int]func(string) (any, any){
@@ -22,6 +23,7 @@ var days = map[int]func(string) (any, any){
 	3: day03.Run,
 	4: day04.Run,
 	5: day05.Run,
+	6: day06.Run,
 }
 
 var rootCmd = &cobra.Command{

2025/day06/day06.go

@@ -0,0 +1,151 @@
+package day06
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func findBlocks(grid [][]rune) [][2]int {
+	rows, cols := len(grid), len(grid[0])
+	blocks := [][2]int{}
+	inBlock, blockStart := false, 0
+	for col := range cols {
+		isSpaceCol := true
+		for row := range rows {
+			if grid[row][col] != ' ' {
+				isSpaceCol = false
+				break
+			}
+		}
+		if !isSpaceCol && !inBlock {
+			inBlock = true
+			blockStart = col
+		}
+		if isSpaceCol && inBlock {
+			inBlock = false
+			blocks = append(blocks, [2]int{blockStart, col - 1})
+		}
+	}
+	if inBlock {
+		blocks = append(blocks, [2]int{blockStart, cols - 1})
+	}
+	return blocks
+}
+
+func getOperation(grid [][]rune, start, end int) string {
+	row := len(grid) - 1
+	opStr := ""
+	for col := start; col <= end; col++ {
+		opStr += string(grid[row][col])
+	}
+	return strings.TrimSpace(opStr)
+}
+
+func computeResult(numbers []int, opStr string) int {
+	if len(numbers) == 0 || opStr == "" {
+		return 0
+	}
+	result := numbers[0]
+	for i := 1; i < len(numbers); i++ {
+		switch opStr[0] {
+		case '+':
+			result += numbers[i]
+		case '*':
+			result *= numbers[i]
+		}
+	}
+	return result
+}
+
+func Part1(grid [][]rune) int {
+	blocks := findBlocks(grid)
+	total := 0
+
+	for _, block := range blocks {
+		start, end := block[0], block[1]
+		rows := len(grid)
+		numbers := []int{}
+		for row := 0; row < rows-1; row++ {
+			numStr := ""
+			for col := start; col <= end; col++ {
+				numStr += string(grid[row][col])
+			}
+
+			numStr = strings.TrimSpace(numStr)
+			if numStr != "" {
+				var num int
+				fmt.Sscanf(numStr, "%d", &num)
+				numbers = append(numbers, num)
+			}
+		}
+
+		opStr := getOperation(grid, start, end)
+		total += computeResult(numbers, opStr)
+	}
+
+	return total
+}
+
+func Part2(grid [][]rune) int {
+	blocks := findBlocks(grid)
+	total := 0
+	for _, block := range blocks {
+		start, end := block[0], block[1]
+		rows := len(grid)
+		numbers := []int{}
+		for col := end; col >= start; col-- {
+			digits := []rune{}
+			for row := 0; row < rows-1; row++ {
+				d := grid[row][col]
+				if d != ' ' {
+					digits = append(digits, d)
+				}
+			}
+
+			numStr := strings.TrimSpace(string(digits))
+			if numStr != "" {
+				var num int
+				fmt.Sscanf(numStr, "%d", &num)
+				numbers = append(numbers, num)
+			}
+		}
+
+		opStr := getOperation(grid, start, end)
+		total += computeResult(numbers, opStr)
+	}
+
+	return total
+}
+
+func Run(filename string) (any, any) {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	lines := []string{}
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if len(line) > 0 {
+			lines = append(lines, line)
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+
+	rows := len(lines)
+	grid := make([][]rune, rows)
+	for i := range lines {
+		grid[i] = []rune(lines[i])
+	}
+
+	part1 := Part1(grid)
+	part2 := Part2(grid)
+
+	return part1, part2
+}

2025/day06/day06_test.go

@@ -0,0 +1,34 @@
+package day06
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    any
+	Part2    any
+}
+
+func TestDay06(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 4277556, 3263827},
+		{"input.txt", 7326876294741, 10756006415204},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2025/day06/test.txt

@@ -0,0 +1,4 @@
+123 328  51 64 
+ 45 64  387 23 
+  6 98  215 314
+*   +   *   +