Runtime: 19 ms (Top 53.0%) | Memory: 44.86 MB (Top 93.0%)

Author: AnasImloul

scripts/algorithms/A/All Elements in Two Binary Search Trees/All Elements in Two Binary Search Trees.java

@@ -1,31 +1,32 @@
-    class Solution {
-public List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
-List<Integer> mylist= new ArrayList<>();
-   
-	there(root1, mylist);
-    there(root2, mylist);
-    
-    int[] arr= new int[mylist.size()];
-    for(int i=0; i<arr.length; i++){
-        arr[i]=mylist.get(i);
+// Runtime: 19 ms (Top 53.0%) | Memory: 44.86 MB (Top 93.0%)
+
+class Solution {
+    public List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
+        Stack<TreeNode> st1 = new Stack<>();
+        Stack<TreeNode> st2 = new Stack<>();
+        
+        List<Integer> res = new ArrayList<>();
+        
+        while(root1 != null || root2 != null || !st1.empty() || !st2.empty()){
+            while(root1 != null){
+                st1.push(root1);
+                root1 = root1.left;
+            }
+            while(root2 != null){
+                st2.push(root2);
+                root2 = root2.left;
+            }
+            if(st2.empty() || (!st1.empty() && st1.peek().val <= st2.peek().val)){
+                root1 = st1.pop();
+                res.add(root1.val);
+                root1 = root1.right;
+            }
+            else{
+                root2 = st2.pop();
+                res.add(root2.val);
+                root2 = root2.right;
+            }
+        }
+        return res;
     }
-    Arrays.sort(arr);
-    List<Integer> now= new ArrayList<>();
-    for(int j: arr){
-        now.add(j);
-    }
-    return now;
-}
-public void there(TreeNode root, List<Integer> map){
-if(root==null){
-    return;
-}
-map.add(root.val);
-if(root.left!=null){
-    there(root.left, map);
-}
-if(root.right!=null){
-    there(root.right, map);
-}
-}
-}
+}