Update 189. 轮转数组.md

Author: CompetitiveLin

Methodology/189. 轮转数组.md

@@ -47,6 +47,7 @@
 另外，如果是 **向左轮转**，则是先反转整个数组，再各自反转 `[0, n - 1 - (k mod n)]` 和 `[n - (k mod n), n - 1]`。
 
 ```Java
+// Java
 class Solution {
     public void rotate(int[] nums, int k) {
         int n = nums.length;
@@ -66,4 +67,36 @@ class Solution {
         }
     }
 }
+```
+
+```go
+// Go
+func rotate(nums []int, k int)  {
+    n := len(nums)
+    reverse(nums, 0, n - 1 - k)
+    reverse(nums, n - k, n - 1)
+    reverse(nums, 0, n - 1)
+}
+
+func reverse(nums []int, left, right int) {
+    for ;left < right; {
+        nums[left], nums[right] = nums[right], nums[left]
+        left++
+        right--
+    }
+}
+```
+
+方法二：额外数组
+
+```go
+func rotate(nums []int, k int)  {
+    n := len(nums)
+    arr := make([]int, n)
+    k = k % n
+    for index := range nums {
+        arr[index] = nums[(n - k + index) % n]
+    }
+    copy(nums, arr)
+}
 ```