Add solution for Day 1

one/main.go

@@ -1,16 +1,24 @@
 package one
 
+import "fmt"
+
 type One struct {
+	radar radar
 }
 
 func Init(filepath string) *One {
-	return nil
+	one := &One{
+		radar: radar{},
+	}
+
+	one.radar.scan(filepath)
+	return one
 }
 
 func (d *One) Answer() string {
-	return "Hello"
+	return fmt.Sprintf("There were %d increases in depth", d.radar.depthIncreases())
 }
 
 func (d *One) FollowUp() string {
-	return "World!"
+	return fmt.Sprintf("There were %d increases in depth when sampling a window", d.radar.windowedDepthIncreases())
 }

one/radar.go

@@ -0,0 +1,66 @@
+package one
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+)
+
+type radar struct {
+	input []int
+}
+
+// scan Loads the data from input.txt into radar
+func (r *radar) scan(filename string) error {
+	r.input = []int{}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		depth, err := strconv.Atoi(scanner.Text())
+		if err != nil {
+			return err
+		}
+		r.input = append(r.input, depth)
+	}
+
+	return nil
+}
+
+// countIncreases for a given array of numbers how many times does one value increment after another
+func countIncreases(input []int) int {
+	increases := 0
+	previousValue := -1
+
+	for _, value := range input {
+		if previousValue == -1 {
+			previousValue = value
+			continue
+		}
+
+		if value > previousValue {
+			increases++
+		}
+		previousValue = value
+	}
+	return increases
+}
+
+func (r *radar) depthIncreases() int {
+	return countIncreases(r.input)
+}
+
+func (r *radar) windowedDepthIncreases() int {
+	windowedDepths := []int{}
+	for i := 0; i < len(r.input)-2; i++ {
+		value := r.input[i] + r.input[i+1] + r.input[i+2]
+		windowedDepths = append(windowedDepths, value)
+	}
+
+	return countIncreases(windowedDepths)
+}

one/radar_test.go

@@ -0,0 +1,52 @@
+package one
+
+import "testing"
+
+var testInput = []int{
+	199,
+	200,
+	208,
+	210,
+	200,
+	207,
+	240,
+	269,
+	260,
+	263,
+}
+
+func Test_scan(t *testing.T) {
+	r := radar{}
+	if err := r.scan("input.txt"); err != nil {
+		t.FailNow()
+	}
+
+	if len(r.input) != 2000 {
+		t.Logf("Expected 2000 entries, found %d", len(r.input))
+		t.Fail()
+	}
+}
+
+func Test_depthIncreases(t *testing.T) {
+	r := radar{
+		input: testInput,
+	}
+
+	increases := r.depthIncreases()
+	if increases != 7 {
+		t.Logf("Expected 7 increases, found %d", increases)
+		t.FailNow()
+	}
+}
+
+func Test_windowDepthIncrease(t *testing.T) {
+	r := radar{
+		input: testInput,
+	}
+
+	increases := r.windowedDepthIncreases()
+	if increases != 5 {
+		t.Logf("Expected 5 increases, found %d", increases)
+		t.FailNow()
+	}
+}