Maximum Depth of Binary Tree

1. Question

求二叉树的最大深度。

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

2. Solution

考虑特殊情况：

• 树为空

采用分治法：

• 左子树的最大深度lh
• 右子树的最大深度rh
• res = 1 + max( lh, rh )

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int maxDepth(TreeNode root) {
        int maxDepth = 0;
        if( root != null ){
            int leftDepth = maxDepth(root.left);
            int rightDepth = maxDepth(root.right);
            maxDepth = (leftDepth>rightDepth ? leftDepth : rightDepth) + 1;
        }
        return maxDepth;
    }
}