Boundary Traversal Problem Statement

Given a binary tree of integers, your task is to return the boundary nodes of this binary tree in an anti-clockwise direction starting from the root node.

Example:

Input:

T = 1
Data for binary tree (in level order):
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

1 2 4 7 6 3

Explanation:

The boundary nodes are the nodes on the left boundary, followed by leaves, followed by right boundary nodes without repeating any nodes.

Constraints:

1 ≤ T ≤ 10²

1 ≤ N ≤ 2¹²

'N' is the total number of nodes in the binary tree.

Time Limit: 1 sec

Note:

The input format was provided for clarity. Each test case should be processed with the entire node sequence given in a single line, separated by spaces where -1 denotes null nodes.

Question

Boundary Traversal Problem Statement

Given a binary tree of integers, your task is to return the boundary nodes of this binary tree in an anti-clockwise direction starting from the root node.

Example:

Input:

T = 1
Data for binary tree (in level order):
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

1 2 4 7 6 3

Explanation:

The boundary nodes are the nodes on the left boundary, followed by leaves, followed by right boundary nodes without repeating any nodes.

Constraints:

1 ≤ T ≤ 10²
1 ≤ N ≤ 2¹²
'N' is the total number of nodes in the binary tree.
Time Limit: 1 sec

Note:

The input format was provided for clarity. Each test case should be processed with the entire node sequence given in a single line, separated by spaces where -1 denotes null nodes.

Accepted Answer

Return the boundary nodes of a binary tree in an anti-clockwise direction starting from the root node.

Traverse the left boundary nodes in a top-down manner
Traverse the leaf nodes from left to right
Traverse the right boundary nodes in a bottom-up manner
Avoid repeating nodes in the output
Example: For input 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1, output should be 1 2 4 7 6 3