如果记得 3.3binary search tree里面关于height的code,就可以瞬间写出bug free的solution了。
以下是3.3binary search tree里面关于height的code:
/** * Returns the height of the BST (for debugging). * * @return the height of the BST (a 1-node tree has height 0) */ public int height() { return height(root); } private int height(Node x) { if (x == null) return -1; return 1 + Math.max(height(x.left), height(x.right)); } //以下是104题的解法: /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public int maxDepth(TreeNode root) { if (root == null) return 0; return 1 + Math.max(root.left, root.right); } }