Method maxDepth

TreeMaxDepthBinaryTree.java:2–7

(TreeNode root)

class Solution {
    public int maxDepth(TreeNode root) {
        if(root==null) return 0;
        int lh = maxDepth(root.left);
        int rh = maxDepth(root.right);
        return 1+Math.max(lh,rh);
    }
}