添加0222.完全二叉树的节点个数Go版本.md

problems/0222.完全二叉树的节点个数.md

@@ -437,6 +437,33 @@ func countNodes(root *TreeNode) int {
 }
 ```
 
+迭代法
+
+```go
+func countNodes(root *TreeNode) int {
+    if root == nil {
+        return 0
+    }
+    q := list.New()
+    q.PushBack(root)
+    res := 0
+    for q.Len() > 0 {
+        n := q.Len()
+        for i := 0; i < n; i++ {
+            node := q.Remove(q.Front()).(*TreeNode)
+            if node.Left != nil {
+                q.PushBack(node.Left)
+            }
+            if node.Right != nil {
+                q.PushBack(node.Right)
+            }
+            res++
+        }
+    }
+    return res 
+}
+```
+
 
 
 ## JavaScript: