Refactor counting sort and add test

Author: vdnhi

sorts/bubble_sort.go renamed to sorts/bubblesort.go

@@ -1,4 +1,3 @@
-// Package sorts a package for demonstrating sorting algorithms in Go
 // Implementation of basic bubble sort algorithm
 // Reference: https://en.wikipedia.org/wiki/Bubble_sort
 

sorts/counting_sort.go

@@ -0,0 +1,27 @@
+// Reference: https://en.wikipedia.org/wiki/Counting_sort
+
+package sorts
+
+func countingSort(arr []int) []int {
+	if len(arr) == 0 {
+		return make([]int, 0)
+	}
+	maxElement := arr[0]
+	for i := 1; i < len(arr); i++ {
+		if arr[i] > maxElement {
+			maxElement = arr[i]
+		}
+	}
+
+	counts := make([]int, maxElement+1)
+	result := make([]int, 0)
+	for _, item := range arr {
+		counts[item]++
+	}
+	for i := 0; i <= maxElement; i++ {
+		for j := 0; j < counts[i]; j++ {
+			result = append(result, i)
+		}
+	}
+	return result
+}

sorts/countingsort.go

@@ -2,8 +2,6 @@ package sorts
 
 import "testing"
 
-//BEGIN TESTS
-
 func TestBubble(t *testing.T) {
 	for _, test := range sortTests {
 		actual := bubbleSort(test.input)
@@ -17,6 +15,19 @@ func TestBubble(t *testing.T) {
 	}
 }
 
+func TestCountingSort(t *testing.T) {
+	for _, testcase := range sortTests {
+		actual := countingSort(testcase.input)
+		pos, sorted := compareSlices(actual, testcase.expected)
+		if !sorted {
+			if pos == -1 {
+				t.Errorf("test %s failed due to slice length changing", testcase.name)
+			}
+			t.Errorf("test %s failed at index %d", testcase.name, pos)
+		}
+	}
+}
+
 func TestSelection(t *testing.T) {
 	for _, test := range sortTests {
 		actual := selectionSort(test.input)
@@ -95,22 +106,6 @@ func TestShell(t *testing.T) {
 	}
 }
 
-/*func TestTopological(t *testing.T) {
-	for _, test := range sortTests {
-		actual := topologicalSort(test.input)
-		pos, sorted := compareSlices(actual, test.expected)
-		if !sorted {
-			if pos == -1 {
-				t.Errorf("test %s failed due to slice length changing", test.name)
-			}
-			t.Errorf("test %s failed at index %d", test.name, pos)
-		}
-	}
-}*/
-
-//END TESTS
-
-//BEGIN BENCHMARKS
 func BenchmarkBubble(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		for _, test := range sortTests {
@@ -167,16 +162,6 @@ func BenchmarkShell(b *testing.B) {
 	}
 }
 
-/*func BenchmarkTopological(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		for _, test := range sortTests {
-			topologicalSort(test.input)
-		}
-	}
-}*/
-
-//END BENCHMARKS
-
 func compareSlices(a []int, b []int) (int, bool) {
 	if len(a) != len(b) {
 		return -1, false