LeetCode-104.Maxinum 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.

Note: A leaf is a node with no children.

Example:

Given binary tree [3,9,20,null,null,15,7],

return its depth = 3.

1 public int maxDepth(TreeNode root) {//树 递归 my
2         if(null==root){
3             return 0;
4         }
5         int ld=maxDepth(root.left);
6         int lr = maxDepth(root.right);
7         int d = ld>lr?(ld+1):(lr+1);
8         return d;
9     }

还可以使用BFS