add day 1

day1/compare_lists.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "strings"
+    "strconv"
+    "sort"
+)
+
+func check(e error) {
+    if e != nil {
+        panic(e)
+    }
+}
+
+func abs(n int) int {
+	if n < 0 {
+		return -n
+	}
+	return n
+}
+
+func main() {
+    // read in file as lines
+    dat, err := os.ReadFile("data.txt")
+    check(err)
+    
+    lines := strings.Split(string(dat), "\n")
+
+    // construct lists
+    left_list := []int{}
+    right_list := []int{}
+
+    for i := range len(lines) - 1 {
+        numbers := strings.Split(lines[i], "   ")
+
+        left_num, err := strconv.Atoi(numbers[0])
+        check(err)
+        right_num, err := strconv.Atoi(numbers[1])
+        check(err)
+
+        left_list = append(left_list, left_num)
+        right_list = append(right_list, right_num)
+    }
+    
+    // sort lists
+    sort.Ints(left_list)
+    sort.Ints(right_list)
+
+    // count difference
+    distance := 0
+    for i := range left_list {
+        distance += abs(left_list[i] - right_list[i])
+    }
+
+    fmt.Println(distance)
+}

day1/similarity_score.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "strings"
+    "strconv"
+    "sort"
+)
+
+func check(e error) {
+    if e != nil {
+        panic(e)
+    }
+}
+
+func count_sorted(list []int, elem int) int {
+    counter := 0
+    for i := range list {
+        if list[i] == elem {
+            counter++
+        } else if counter > 0 {
+            break
+        }
+    }
+    return counter
+}
+
+func main() {
+    // read in file as lines
+    dat, err := os.ReadFile("data.txt")
+    check(err)
+    
+    lines := strings.Split(string(dat), "\n")
+
+    // construct lists
+    left_list := []int{}
+    right_list := []int{}
+
+    for i := range len(lines) - 1 {
+        numbers := strings.Split(lines[i], "   ")
+
+        left_num, err := strconv.Atoi(numbers[0])
+        check(err)
+        right_num, err := strconv.Atoi(numbers[1])
+        check(err)
+
+        left_list = append(left_list, left_num)
+        right_list = append(right_list, right_num)
+    }
+    
+    // sort right_list
+    sort.Ints(right_list)
+
+    // count similarity
+    score := 0
+    for i := range left_list {
+        score += left_list[i] * count_sorted(right_list, left_list[i])
+    }
+
+    fmt.Println(score)
+}