Determine the Left View of a Binary Tree

You are given a binary tree of integers. Your task is to determine the left view of the binary tree. The left view consists of nodes that are visible when the tree is viewed from the left side.

Example:

Input:

T = 1
Binary Tree Level Order Input: 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

1 2 4 7

Explanation:

The left view of the binary tree is 1, 2, 4, 7 as shown in the image below:

Constraints:

• 1 <= T <= 100
• 0 <= N <= 3000
• 1 <= data <= 10⁵ and data ≠ -1

Note:

You do not need to handle any input/output operations; just implement the function to return the required result.