Add golang implementation for Deque

Author: leandronsp

README.md

@@ -1713,7 +1713,7 @@ Com o objetivo de alcançar uma abrangência maior e encorajar mais pessoas a co
                 </a>
             </td>
             <td> <!-- Go -->
-                <a href="./CONTRIBUTING.md">
+                <a href="./src/go/deque.go">
                     <img align="center" height="25" src="https://cdn.jsdelivr.net/gh/devicons/devicon/icons/github/github-original.svg" />
                 </a>
             </td>

src/go/deque.go

@@ -0,0 +1,64 @@
+import (
+  "testing"
+  "github.com/stretchr/testify/assert"
+)
+
+type Deque struct {
+  Store []int
+}
+
+// Time complexity: O(1)
+func (deque *Deque) RPush(element int) {
+  deque.Store = append(deque.Store, element)
+}
+
+// Time complexity: O(n)
+func (deque *Deque) LPush(element int) {
+  deque.Store = append([]int{element}, deque.Store...)
+}
+
+// Time complexity: O(1)
+func (deque *Deque) RPop() *int {
+  if len(deque.Store) == 0 {
+    return nil
+  }
+
+  element := deque.Store[len(deque.Store) - 1]
+  deque.Store = deque.Store[:len(deque.Store) - 1]
+
+  return &element
+}
+
+// Time complexity: O(n)
+func (deque *Deque) LPop() *int {
+  if len(deque.Store) == 0 {
+    return nil
+  }
+
+  element := deque.Store[0]
+  deque.Store = deque.Store[1:]
+
+  return &element
+}
+
+func TestDeque(t *testing.T) {
+  deque := Deque{}
+
+  deque.RPush(1)
+  deque.RPush(2)
+  deque.RPush(3)
+
+  assert.Equal(t, 3, *deque.RPop())
+  assert.Equal(t, 2, *deque.RPop())
+  assert.Equal(t, 1, *deque.RPop())
+  assert.Nil(t, deque.RPop())
+
+  deque.LPush(1)
+  deque.LPush(2)
+  deque.LPush(3)
+
+  assert.Equal(t, 1, *deque.RPop())
+  assert.Equal(t, 2, *deque.RPop())
+  assert.Equal(t, 3, *deque.RPop())
+  assert.Nil(t, deque.RPop())
+}