Algo.Leetcode.111. Minimum Depth of Binary Tree

Task

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

Note: A leaf is a node with no children.

Example 1:

Input: root = [3,9,20,null,null,15,7]
Output: 2

Example 2:

Input: root = [2,null,3,null,4,null,5,null,6]
Output: 5

Constraints:

• The number of nodes in the tree is in the range [0, 105].
• -1000 <= Node.val <= 1000

Decision

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
public class Solution {
    public int MinDepth(TreeNode root) {
        
        if (root  == null)
            return 0;
              
        var left = 0;
        var right = 0;
        
        Console.WriteLine("root {0} left {1} right {2}", root.val, root.left, root.right);
        
        if (root.left == null && root.right == null) {
            return 1;
        }
                
        if (root.left != null) {
            left =  1 + MinDepth(root.left);
        }
                
        
        if (root.right != null) {
            right = 1 + MinDepth(root.right);
        }
        
        if (left != 0 && right != 0)
          return Math.Min(left, right);
        else
          return Math.Max(left, right);  
    }
}