14_sorts by golang

go/14_sorts/CountingSort.go

@@ -0,0 +1,33 @@
+package _4_sorts
+
+import "math"
+
+func CountingSort(a []int, n int) {
+	if n <= 1 {
+		return
+	}
+
+	var max int = math.MinInt32
+	for i := range a {
+		if a[i] > max {
+			max = a[i]
+		}
+	}
+
+	c := make([]int, max+1)
+	for i := range a {
+		c[a[i]]++
+	}
+	for i := 1; i <= max; i++ {
+		c[i] += c[i-1]
+	}
+
+	r := make([]int, n)
+	for i := range a {
+		index := c[a[i]] - 1
+		r[index] = a[i]
+		c[a[i]]--
+	}
+
+	copy(a, r)
+}

go/14_sorts/CountingSort_test.go

@@ -0,0 +1,13 @@
+package _4_sorts
+
+import "testing"
+
+func TestCountingSort(t *testing.T) {
+	arr := []int{5, 4}
+	CountingSort(arr, len(arr))
+	t.Log(arr)
+
+	arr = []int{5, 4, 3, 2, 1}
+	CountingSort(arr, len(arr))
+	t.Log(arr)
+}