From 09b6461396359e579310fc1c470260efd436b62f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?leotyliu=28=E5=88=98=E5=A4=A9=E4=B8=80=29?=
 <leotyliu@tencent.com>
Date: Mon, 22 Oct 2018 17:00:12 +0800
Subject: [PATCH] 14_sorts by golang

---
 go/14_sorts/CountingSort.go      | 33 ++++++++++++++++++++++++++++++++
 go/14_sorts/CountingSort_test.go | 13 +++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 go/14_sorts/CountingSort.go
 create mode 100644 go/14_sorts/CountingSort_test.go

diff --git a/go/14_sorts/CountingSort.go b/go/14_sorts/CountingSort.go
new file mode 100644
index 0000000..834a2c1
--- /dev/null
+++ b/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)
+}
diff --git a/go/14_sorts/CountingSort_test.go b/go/14_sorts/CountingSort_test.go
new file mode 100644
index 0000000..c6f5b46
--- /dev/null
+++ b/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)
+}