2017-day2: more modulo stuff

2017/day02/main.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/mathutil"
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	if part == 1 {
+		ans := part1(util.ReadFile("./input.txt"))
+		fmt.Println("Output:", ans)
+	} else {
+		ans := part2(util.ReadFile("./input.txt"))
+		fmt.Println("Output:", ans)
+	}
+}
+
+func part1(input string) int {
+	rows := parseInput(input)
+	var checksum int
+	for _, r := range rows {
+		checksum += mathutil.MaxInt(r...) - mathutil.MinInt(r...)
+	}
+	return checksum
+}
+
+func part2(input string) int {
+	rows := parseInput(input)
+	var sumDivisible int
+	for _, r := range rows {
+		for i, val1 := range r {
+			for _, val2 := range r[i+1:] {
+				if val1%val2 == 0 {
+					sumDivisible += val1 / val2
+					break
+				} else if val2%val1 == 0 {
+					sumDivisible += val2 / val1
+					break
+				}
+			}
+		}
+	}
+	return sumDivisible
+}
+
+func parseInput(input string) (ans [][]int) {
+	lines := strings.Split(input, "\n")
+	for i, l := range lines {
+		ans = append(ans, []int{})
+		// split by tabs
+		for _, num := range strings.Split(l, "\t") {
+			ans[i] = append(ans[i], mathutil.StrToInt(num))
+		}
+	}
+	return ans
+}

2017/day02/main_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 30994},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 233},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}