Leetcode 513 | Find Bottom Left Tree Value | Medium Level Tree problem (Java Solution)

Find Bottom Left Tree Value problem of leetcode states:

Given a binary tree, find the leftmost value in the last row of the tree.
Example 1:
Input:

2
/ \
1 3

Output:
1
Example 2:
Input:

1
/ \
2 3
/ / \
4 5 6
/
7

Output:
7