Maximum Depth of Binary Tree

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.

一样的。

/**
 * 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) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ArrayList<TreeNode> queue = new ArrayList<TreeNode>();
        int result = 0;
        if(root == null) return result;
        queue.add(root);
        TreeNode nl = new TreeNode(Integer.MIN_VALUE);
        queue.add(nl);
        while(queue.size() != 1){
            TreeNode rn = queue.remove(0);
            if(rn.val == Integer.MIN_VALUE){
                queue.add(nl);
                result ++;
            }
            else{
                if(rn.left != null) queue.add(rn.left);
                if(rn.right != null) queue.add(rn.right);
            }
        }
        return ++result;
    }
}