Minimum Depth of a Binary Tree

Determine the minimum depth of an integer-based binary tree. The minimum depth is defined as the number of nodes present along the shortest path from the root node down to the nearest leaf node.

Input:

The first line contains an integer 'T', denoting the number of test cases. Each test case comprises tree elements in level order form. Utilize -1 to denote a null node.

Output:

Output the minimum depth of the binary tree for each test case, each on a new line.

Example:

Input:

1
2 3
4 -1 5 6
-1 7 -1 -1 -1 -1
-1 -1

Output:

2

Explanation:

The shortest path is from the root node 1 to the leaf node 2, traversing 2 nodes, resulting in a minimum depth of 2.

Constraints:

• 1 <= T <= 10^2
• 0 <= N <= 10^3

Note: A leaf is defined as a node without children.