Given a Binary Tree, find the In-Order Traversal of it.

Example 1:

Input:
       1
     /  \
    3    2
Output: 3 1 2

Example 2:

Input:
        10
     /      \ 
    20       30 
  /    \    /
 40    60  50
Output: 40 20 60 10 50 30

Your Task:
You don't need to read input or print anything. Your task is to complete the function inOrder() that takes root node of the tree as input and returns a list containing the In-Order Traversal of the given Binary Tree.

Expected Time Complexity: O(N).
Expected Auxiliary Space: O(N).

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