Homework

exercises/Fibonacci/main.go

@@ -0,0 +1,18 @@
+package main
+
+import "fmt"
+
+func fibonacci(n, a, b int, s []int) []int {
+	if n > 0 {
+		s = append(s, a)
+		return fibonacci(n-1, b, a+b, s)
+	}
+	return s
+}
+
+func main() {
+	var n int
+	var s []int
+	fmt.Scan(&n)
+	fmt.Println(fibonacci(n, 0, 1, s))
+}

exercises/Fibonacci/main_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestFibonacci(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		n    int
+		a    int
+		b    int
+		s    []int
+		want []int
+	}{
+		{"1", 1, 0, 1, []int{}, []int{0, 1}},
+		{"2", 8, 0, 1, []int{}, []int{0, 1, 1, 2, 3, 5, 8, 13, 21}},
+		{"3", -1, 0, 1, []int{}, []int{}},
+		{"4", 5, 0, 1, []int{}, []int{0, 1, 1, 2, 3}},
+		{"5", 0, 0, 1, []int{}, []int{0}},
+		{"6", 2, 0, 1, []int{}, []int{0, 1, 1}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := fibonacci(tc.n, tc.a, tc.b, tc.s)
+			if reflect.DeepEqual(got, tc.want) {
+				t.Errorf("got = %v, want = %v", got, tc.want)
+			}
+		})
+	}
+}

exercises/IsPowerOf2/main.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func ispowerof2(n int) bool {
+	if n%2 != 0 {
+		return false
+	}
+	if n == 2 || n == 1 {
+		return true
+	}
+	return ispowerof2(n / 2)
+}
+
+func main() {
+	var n int
+	fmt.Scan(&n)
+	fmt.Println(ispowerof2(n))
+}

exercises/IsPowerOf2/main_test.go

@@ -0,0 +1,21 @@
+package main
+
+import "testing"
+
+func TestIspowerof2(t *testing.T) {
+	for _, tc := range []struct {
+		n    int
+		want bool
+	}{
+		{512, true},
+		{128, true},
+		{9, false},
+		{3, false},
+		{64, true},
+		{31, false},
+	} {
+		if got := ispowerof2(tc.n); got != tc.want {
+			t.Errorf("powerof2(%v)   got = %v, want = %v", tc.n, got, tc.want)
+		}
+	}
+}

exercises/Maxnumber/main.go

@@ -0,0 +1,41 @@
+package main
+
+import "fmt"
+
+func maxnumber(s []int, max, a int) int {
+	if len(s) == 1 {
+		return max
+	}
+	if a < len(s) {
+		if max < s[a] {
+			max = s[a]
+		}
+		return maxnumber(s, max, a+1)
+	}
+	return max
+}
+
+func maxnumber2nd(s []int, max, max2, a int) int {
+	if len(s) == 1 {
+		return max
+	}
+	if max < max2 {
+		max, max2 = max2, max
+	}
+	if a < len(s) {
+		if max < s[a] {
+			max2 = max
+			max = s[a]
+		} else if max2 < s[a] {
+			max2 = s[a]
+		}
+		return maxnumber2nd(s, max, max2, a+1)
+	}
+	return max2
+}
+
+func main() {
+	s := []int{1000, 1001, -100, 1}
+	fmt.Println(maxnumber(s, s[0], 1))
+	fmt.Println(maxnumber2nd(s, s[0], s[1], 2))
+}

exercises/Maxnumber/main_test.go

@@ -0,0 +1,38 @@
+package main
+
+import "testing"
+
+func TestMaxnumber(t *testing.T) {
+	for _, tc := range []struct {
+		n    []int
+		max  int
+		i    int
+		want int
+	}{
+		{[]int{1000, 1001, -100, 1}, 1000, 1, 1001},
+		{[]int{1, -3, 99, 675}, 1, 1, 675},
+		{[]int{10, 11, -100, 1}, 10, 1, 11},
+	} {
+		if max := maxnumber(tc.n, tc.max, tc.i); max != tc.want {
+			t.Errorf("numSum(%v) got = %v, want = %v", tc.n, max, tc.want)
+		}
+	}
+}
+
+func TestMaxnumber2nd(t *testing.T) {
+	for _, tc := range []struct {
+		n    []int
+		max  int
+		max2 int
+		i    int
+		want int
+	}{
+		{[]int{1000, 1001, -100, 1}, 1000, 1001, 2, 1000},
+		{[]int{1, -3, 99, 675}, 1, -3, 2, 99},
+		{[]int{10, 11, -100, 1}, 10, 11, 2, 10},
+	} {
+		if max := maxnumber2nd(tc.n, tc.max, tc.max2, tc.i); max != tc.want {
+			t.Errorf("numSum(%v) got = %v, want = %v", tc.n, max, tc.want)
+		}
+	}
+}

exercises/Numbers/main.go

@@ -0,0 +1,25 @@
+package main
+
+import "fmt"
+
+func numbers(n, a int) {
+	if n == 0 {
+		return
+	}
+	fmt.Println(a)
+	numbers(n-1, a+1)
+}
+func numbers2(n int) {
+	if n == 0 {
+		return
+	}
+	fmt.Println(n)
+	numbers2(n - 1)
+}
+
+func main() {
+	var n, a int
+	fmt.Scan(&n)
+	numbers(n, a)
+	numbers2(n)
+}

exercises/Sumdigits/main.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func sumdigits(n int) int {
+	if n == 0 {
+		return 0
+	}
+	return n%10 + sumdigits(n/10)
+}
+
+func main() {
+	var n int
+	fmt.Scan(&n)
+	fmt.Println(sumdigits(n))
+}

exercises/Sumdigits/main_test.go

@@ -0,0 +1,21 @@
+package main
+
+import "testing"
+
+func TestSumdigits(t *testing.T) {
+	for _, tc := range []struct {
+		n    int
+		want int
+	}{
+		{333, 9},
+		{321, 6},
+		{21, 3},
+		{10000, 1},
+		{420, 6},
+		{228, 12},
+	} {
+		if got := sumdigits(tc.n); got != tc.want {
+			t.Errorf("numSum(%v)   got = %v, want = %v", tc.n, got, tc.want)
+		}
+	}
+}