<go-implement><quicksort & mergesort>

implement insertsort and selectsort and shellsort in go version

signed-off-by: ray1888

Author: ray1888

go/src/algocasts/insertsort.go

@@ -0,0 +1,16 @@
+package algocasts
+
+func insertsort(input []int) {
+	if input == nil || len(input) == 0 {
+		return
+	}
+	for i := 1; i < len(input); i++ {
+		cur := input[i]
+		j := i - 1
+		for j >= 0 && input[j] > cur {
+			input[j+1] = input[j]
+			j -= 1
+		}
+		input[j+1] = cur
+	}
+}

go/src/algocasts/insertsort_test.go

@@ -0,0 +1,22 @@
+package algocasts
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestInsertSort(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []int
+		want  []int
+	}{
+		{"double", []int{2, 1}, []int{1, 2}},
+		{"single", []int{1, 5, 4}, []int{1, 4, 5}},
+		{"normal", []int{1, 9, 5, 3, 2, 6}, []int{1, 2, 3, 5, 6, 9}},
+	}
+	for _, tt := range tests {
+		insertsort(tt.input)
+		assert.Equal(t, tt.input, tt.want)
+	}
+}

go/src/algocasts/mergesort_test.go

@@ -17,7 +17,6 @@ func TestMergeSortRecursive(t *testing.T) {
 	}
 	for _, tt := range tests {
 		MergeSortRecursive(tt.input)
-		t.Log(tt.input, tt.want)
 		assert.Equal(t, tt.input, tt.want)
 	}
 }

go/src/algocasts/quicksort.go

@@ -1,11 +1,5 @@
 package algocasts
 
-func swap(array []int, a int, b int) {
-	tmp := array[b]
-	array[b] = array[a]
-	array[a] = tmp
-}
-
 func lomutopartition(input []int, low, high int) int {
 	pivot := input[high]
 	i := low

go/src/algocasts/quicksort_test.go

@@ -17,7 +17,6 @@ func TestQuickSort(t *testing.T) {
 	}
 	for _, tt := range tests {
 		Quicksort(tt.input)
-		t.Log(tt.input, tt.want)
 		assert.Equal(t, tt.input, tt.want)
 	}
 }
@@ -34,7 +33,6 @@ func TestLomutoSort(t *testing.T) {
 	}
 	for _, tt := range tests {
 		Lomutosort(tt.input)
-		t.Log(tt.input, tt.want)
 		assert.Equal(t, tt.input, tt.want)
 	}
 }

go/src/algocasts/selectsort.go

@@ -0,0 +1,31 @@
+package algocasts
+
+func selectsortMin(input []int) {
+	if input == nil || len(input) == 0 {
+		return
+	}
+	for i := 0; i < len(input); i++ {
+		minId := i
+		for j := i + 1; j < len(input); j++ {
+			if input[j] < input[minId] {
+				minId = j
+			}
+		}
+		swap(input, i, minId)
+	}
+}
+
+func selectsortMax(input []int) {
+	if input == nil || len(input) == 0 {
+		return
+	}
+	for i := len(input) - 1; i >= 0; i-- {
+		maxId := i
+		for j := 0; j < i; j++ {
+			if input[j] > input[maxId] {
+				maxId = j
+			}
+		}
+		swap(input, i, maxId)
+	}
+}

go/src/algocasts/selectsort_test.go

@@ -0,0 +1,36 @@
+package algocasts
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestSelectSortMin(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []int
+		want  []int
+	}{
+		{"single", []int{1, 5, 4}, []int{1, 4, 5}},
+		{"normal", []int{1, 9, 5, 3, 2, 6}, []int{1, 2, 3, 5, 6, 9}},
+	}
+	for _, tt := range tests {
+		selectsortMin(tt.input)
+		assert.Equal(t, tt.input, tt.want)
+	}
+}
+
+func TestSelectSortMax(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []int
+		want  []int
+	}{
+		{"single", []int{1, 5, 4}, []int{1, 4, 5}},
+		{"normal", []int{1, 9, 5, 3, 2, 6}, []int{1, 2, 3, 5, 6, 9}},
+	}
+	for _, tt := range tests {
+		selectsortMax(tt.input)
+		assert.Equal(t, tt.input, tt.want)
+	}
+}

go/src/algocasts/shellsort.go

@@ -0,0 +1,19 @@
+package algocasts
+
+func shellsort(input []int) {
+	if input == nil || len(input) == 0 {
+		return
+	}
+	// >>= means bit counting left move
+	for gap := len(input) >> 1; gap > 0; gap >>= 1 {
+		for i := gap; i < len(input); i++ {
+			cur := input[i]
+			j := i - gap
+			for j >= 0 && input[j] > cur {
+				input[j+gap] = input[j]
+				j -= gap
+			}
+			input[j+gap] = cur
+		}
+	}
+}

go/src/algocasts/shellsort_test.go

@@ -0,0 +1,21 @@
+package algocasts
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestShellSort(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []int
+		want  []int
+	}{
+		{"single", []int{1, 5, 4}, []int{1, 4, 5}},
+		{"normal", []int{1, 9, 5, 3, 2, 6}, []int{1, 2, 3, 5, 6, 9}},
+	}
+	for _, tt := range tests {
+		shellsort(tt.input)
+		assert.Equal(t, tt.input, tt.want)
+	}
+}

go/src/algocasts/util.go

@@ -0,0 +1,7 @@
+package algocasts
+
+func swap(array []int, a int, b int) {
+	tmp := array[b]
+	array[b] = array[a]
+	array[a] = tmp
+}