feat: add CountSort

algorithm/sorter.go

@@ -1,7 +1,7 @@
 // Copyright 2021 dudaodong@gmail.com. All rights reserved.
 // Use of this source code is governed by MIT license
 
-// Package algorithm contain some algorithm functions. eg. sort, find, list, linklist, stack, queue, tree, graph. TODO
+// Package algorithm contain some basic algorithm functions. eg. sort, search, list, linklist, stack, queue, tree, graph. TODO
 package algorithm
 
 import "github.com/duke-git/lancet/lancetconstraints"
@@ -183,6 +183,25 @@ func merge[T any](slice []T, low, mid, high int, comparator lancetconstraints.Co
 	}
 }
 
+// CountSort use count sorting for slice
+func CountSort[T any](slice []T, comparator lancetconstraints.Comparator) []T {
+	size := len(slice)
+	out := make([]T, size)
+
+	for i := 0; i < size; i++ {
+		count := 0
+		for j := 0; j < size; j++ {
+			//slice[i] > slice[j]
+			if comparator.Compare(slice[i], slice[j]) == 1 {
+				count++
+			}
+		}
+		out[count] = slice[i]
+	}
+
+	return out
+}
+
 // swap two slice value at index i and j
 func swap[T any](slice []T, i, j int) {
 	slice[i], slice[j] = slice[j], slice[i]

algorithm/sorter_test.go

@@ -151,7 +151,7 @@ func TestHeapSort(t *testing.T) {
 }
 
 func TestMergeSort(t *testing.T) {
-	asssert := internal.NewAssert(t, "TestHeapSort")
+	asssert := internal.NewAssert(t, "TestMergeSort")
 
 	comparator := &peopleAageComparator{}
 	sortedPeopleByAge := MergeSort(peoples, 0, len(peoples)-1, comparator)
@@ -160,5 +160,18 @@ func TestMergeSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", sortedPeopleByAge)
 
+	asssert.Equal(expected, actual)
+}
+
+func TestCountSort(t *testing.T) {
+	asssert := internal.NewAssert(t, "TestCountSort")
+
+	comparator := &peopleAageComparator{}
+	sortedPeopleByAge := CountSort(peoples, comparator)
+	t.Log(sortedPeopleByAge)
+
+	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
+	actual := fmt.Sprintf("%v", sortedPeopleByAge)
+
 	asssert.Equal(expected, actual)
 }