code kata 230811

code_kata_230811/binary_tree_test.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func preOrder(n *node) {
+	stack := MakeStack()
+	p := n
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			visit(p)
+			stack.Push(p)
+			p = p.left
+		} else {
+			p = stack.Pop().(*node)
+			p = p.right
+		}
+	}
+}
+
+func inOrder(n *node) {
+	stack := MakeStack()
+	p := n
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			stack.Push(p)
+			p = p.left
+		} else {
+			p = stack.Pop().(*node)
+			visit(p)
+			p = p.right
+		}
+	}
+}
+
+func postOrder(n *node) {
+	stack := MakeStack()
+	p := n
+	var r *node = nil
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			stack.Push(p)
+			p = p.left
+		} else {
+			p = stack.Top().(*node)
+			if p.right != nil && p.right != r {
+				p = p.right
+				stack.Push(p)
+				p = p.left
+			} else {
+				p = stack.Pop().(*node)
+				visit(p)
+				r = p
+				p = nil
+			}
+		}
+	}
+}
+
+func TestPreOrder(t *testing.T) {
+	preOrder(makeBinaryTree())
+}
+
+func TestInOrder(t *testing.T) {
+	inOrder(makeBinaryTree())
+}
+
+func TestPostOrder(t *testing.T) {
+	postOrder(makeBinaryTree())
+}
+
+func visit(n *node) {
+	if n == nil {
+		return
+	}
+	fmt.Printf("visiting node %s\n", n.value)
+}
+
+type node struct {
+	left  *node
+	right *node
+	value string
+}
+
+func makeBinaryTree() *node {
+	return &node{
+		left: &node{
+			left: &node{
+				value: "D",
+			},
+			right: &node{
+				value: "E",
+			},
+			value: "B",
+		},
+		right: &node{
+			left: &node{
+				value: "F",
+			},
+			right: &node{
+				value: "G",
+			},
+			value: "C",
+		},
+		value: "A",
+	}
+}

code_kata_230811/int_to_string_test.go

@@ -0,0 +1,72 @@
+package main
+
+import "testing"
+
+func IntToString(n int) string {
+	var ret []byte
+	for n > 0 {
+		ret = append(ret, '0'+byte(n%10))
+		n /= 10
+	}
+	return ReverseString(string(ret))
+}
+
+func IntToString2(n int) string {
+	var ret []byte
+	for n > 0 {
+		ret = append([]byte{'0' + byte(n%10)}, ret...)
+		n /= 10
+	}
+	return string(ret)
+}
+
+func ReverseString(s string) string {
+	ret := []rune(s)
+	for l, r := 0, len(ret)-1; l < r; l, r = l+1, r-1 {
+		ret[l], ret[r] = ret[r], ret[l]
+	}
+	return string(ret)
+}
+
+func TestReverseString(t *testing.T) {
+	tt := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{"test", "test", "tset"},
+		{"testing", "testing", "gnitset"},
+		{"i am testing", "i am testing", "gnitset ma i"},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ReverseString(tc.input)
+			if got != tc.want {
+				t.Errorf("ReverseString(%s) = %s, want %s\n", tc.input, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestIntToString(t *testing.T) {
+	tt := []struct {
+		name  string
+		input int
+		want  string
+	}{
+		{"1", 1, "1"},
+		{"12", 12, "12"},
+		{"123", 123, "123"},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			//got := IntToString(tc.input)
+			got := IntToString2(tc.input)
+			if got != tc.want {
+				t.Errorf("IntToString(%d) = %s, want %s\n", tc.input, got, tc.want)
+			}
+		})
+	}
+}

code_kata_230811/prime_factors_test.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func PrimeFactorsOf(n int) []int {
+	ret := make([]int, 0)
+	d := 2
+	for d < n {
+		for n%d == 0 {
+			ret = append(ret, d)
+			n /= d
+		}
+		d++
+	}
+	if n > 1 {
+		ret = append(ret, n)
+	}
+	return ret
+}
+
+func TestPrimeFactorsOf(t *testing.T) {
+	tt := []struct {
+		name  string
+		input int
+		want  []int
+	}{
+		{"1", 1, []int{}},
+		{"2", 2, []int{2}},
+		{"4", 4, []int{2, 2}},
+		{"8", 8, []int{2, 2, 2}},
+		{"9", 9, []int{3, 3}},
+		{"a very large number", 2 * 17 * 37 * 71 * 73, []int{2, 17, 37, 71, 73}},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			got := PrimeFactorsOf(tc.input)
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("PrimeFactorsOf(%d) = %v, want %v\n", tc.input, got, tc.want)
+			}
+		})
+	}
+}

code_kata_230811/stack.go

@@ -0,0 +1,35 @@
+package main
+
+type Stack []interface{}
+
+func MakeStack() *Stack {
+	return &Stack{}
+}
+
+func (s Stack) Len() int {
+	return len(s)
+}
+
+func (s Stack) IsEmpty() bool {
+	return len(s) == 0
+}
+
+func (s Stack) Top() interface{} {
+	if s.IsEmpty() {
+		return nil
+	}
+	return s[len(s)-1]
+}
+
+func (s *Stack) Push(item interface{}) {
+	*s = append(*s, item)
+}
+
+func (s *Stack) Pop() interface{} {
+	if s.IsEmpty() {
+		return nil
+	}
+	ret := (*s)[(*s).Len()-1]
+	*s = (*s)[:len(*s)-1]
+	return ret
+}