#### Loading...

Leaderboard
Showing:
Handle Score
@Ibrahim Nash 6420
@blackshadows 6376
@mb1973 5578
@Quandray 5231
@akhayrutdinov 5111
@saiujwal13083 4510
@sanjay05 3762
@kirtidee18 3673
@marius_valentin_dragoi 3522
@sushant_a 3459
@verma_ji 3412
Complete Leaderboard
Preorder traversal (Iterative)
Medium Accuracy: 87.78% Submissions: 2607 Points: 4

Given a binary tree. Find the preorder traversal of the tree without using recursion.

Example 1

Input:
1
/   \
2     3
/  \
4    5
Output: 1 2 4 5 3
Explanation:
Preorder traversal (Root->Left->Right) of
the tree is 1 2 4 5 3.


Example 2

Input:
8
/   \
1      5
\    /  \
7  10   6
\  /
10 6
Output: 8 1 7 10 5 10 6 6
Explanation:
Inorder traversal (Root->Left->Right)
of the tree is 8 1 7 10 5 10 6 6 .

Your task:

You don't need to read input or print anything. Your task is to complete the function preOrder() which takes the root of the tree as input and returns a list containing the preorder traversal of the tree, calculated without using recursion.

Expected time complexity: O(N)
Expected auxiliary space: O(N)

Constraints:
1 <= Number of nodes <= 105
1 <= Data of a node <= 105

to report an issue on this page.

### Editorial

We strongly recommend solving this problem on your own before viewing its editorial. Do you still want to view the editorial?

#### My Submissions:

Login to access your submissions.

Preorder traversal (Iterative)