104.MaxDepth.cs

// 104. Maximum Depth of Binary Tree

// Given the root of a binary tree, return its maximum depth.

// A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

// Example 1:
// Input: root = [3,9,20,null,null,15,7]
// Output: 3
// Example 2:
// Input: root = [1,null,2]
// Output: 2

/**
 * 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 MaxDepth(TreeNode root) {
        if (root == null)
            return 0;
        int leftHeight, rightHeight;
        leftHeight = rightHeight = 0;
        if (root.left != null)
        {
            leftHeight = MaxDepth(root.left);
        }
        if (root.right != null)
        {
            rightHeight = MaxDepth(root.right);
        }
        return 1 + Math.Max(leftHeight, rightHeight);
    }
}