Day 1 Brian Barbieri

day-01/go_brianbarbieri/main.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"math"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+func main() {
+
+	data_example := readExample()
+	data_input := readInput()
+
+	total := solution1(data_example)
+	fmt.Println("Answer for example solution 1: ", total)
+
+	total = solution1(data_input)
+	fmt.Println("Answer for input solution 1: ", total)
+
+	total = solution2(data_example)
+	fmt.Println("Answer for example solution 2: ", total)
+
+	total = solution2(data_input)
+	fmt.Println("Answer for input solution 2: ", total)
+}
+
+func openFile(filePath string) [][]int {
+	file, err := os.Open(filePath)
+	if err != nil {
+		fmt.Println("Error opening file:", err)
+		return nil
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+
+	// two int lists
+	var left []int
+	var right []int
+
+	// Read each line
+	for scanner.Scan() {
+		line := scanner.Text() // Get the current line as a string
+		// Split the line into parts and parse as integers
+		parts := strings.Fields(line) // Split by whitespace
+		if len(parts) == 2 {          // Ensure there are exactly two numbers
+			left = append(left, toInt(parts[0]))
+			right = append(right, toInt(parts[1]))
+		}
+	}
+
+	return [][]int{left, right}
+}
+
+func readExample() [][]int {
+	return openFile("day1/example.txt")
+}
+
+func readInput() [][]int {
+	return openFile("day1/input.txt")
+}
+
+func toInt(s string) int {
+	i, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return i
+}
+
+func solution1(data [][]int) int {
+	sort.Ints(data[0])
+	sort.Ints(data[1])
+	total := 0
+	for i := 0; i < len(data[0]); i++ {
+		total += int(math.Abs(float64(data[0][i] - data[1][i])))
+	}
+	return total
+}
+
+func solution2(data [][]int) int {
+	counts := make(map[int]int)
+	total := 0
+
+	for _, num := range data[1] { // count each number in right list
+		counts[num]++
+	}
+
+	for _, num := range data[0] { // lookup in left list
+		total += num * counts[num]
+	}
+	return total
+}