diff --git "a/problems/0300.346円234円200円351円225円277円344円270円212円345円215円207円345円255円220円345円272円217円345円210円227円.md" "b/problems/0300.346円234円200円351円225円277円344円270円212円345円215円207円345円255円220円345円272円217円345円210円227円.md"
index e8cb0b5f18..01d349496b 100644
--- "a/problems/0300.346円234円200円351円225円277円344円270円212円345円215円207円345円255円220円345円272円217円345円210円227円.md"
+++ "b/problems/0300.346円234円200円351円225円277円344円270円212円345円215円207円345円255円220円345円272円217円345円210円227円.md"
@@ -149,7 +149,7 @@ class Solution:
 if len(nums) <= 1: return len(nums) dp = [1] * len(nums) - result = 0 + result = 1 for i in range(1, len(nums)): for j in range(0, i): if nums[i]> nums[j]:
diff --git "a/problems/0669.344円277円256円345円211円252円344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円.md" "b/problems/0669.344円277円256円345円211円252円344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円.md"
index 95372d6196..85922a1dd8 100644
--- "a/problems/0669.344円277円256円345円211円252円344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円.md"
+++ "b/problems/0669.344円277円256円345円211円252円344円272円214円345円217円211円346円220円234円347円264円242円346円240円221円.md"
@@ -248,6 +248,8 @@ public:
 
 ## Java
 
+**递归**
+
 ```Java
 class Solution {
 public TreeNode trimBST(TreeNode root, int low, int high) {
@@ -269,6 +271,46 @@ class Solution {
 
 ```
 
+**迭代**
+
+```Java
+class Solution {
+ //iteration
+ public TreeNode trimBST(TreeNode root, int low, int high) {
+ if(root == null)
+ return null;
+ while(root != null && (root.val < low &#124;&#124; root.val> high)){
+ if(root.val < low) + root = root.right; + else + root = root.left; + } + + TreeNode curr = root; + + //deal with root's left sub-tree, and deal with the value smaller than low. + while(curr != null){ + while(curr.left != null && curr.left.val < low){ + curr.left = curr.left.right; + } + curr = curr.left; + } + //go back to root; + curr = root; + + //deal with root's righg sub-tree, and deal with the value bigger than high. + while(curr != null){ + while(curr.right != null && curr.right.val> high){
+ curr.right = curr.right.left;
+ }
+ curr = curr.right;
+ }
+ return root;
+ }
+}
+
+````
+
 ## Python
 
 递归法(版本一)
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