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.
Solution:
1. Recursive:
/** * 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) { if(root == null) return 0; return getDepth(root, 1); } public int getDepth(TreeNode node, int depth) { int left = depth, right = depth; if(node.left != null) left = getDepth(node.left, depth + 1); if(node.right != null) right = getDepth(node.right, depth + 1); return left > right ? left : right; } }
2. Non-recursive:
/** * 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) { if(root == null) return 0; // Non-recursive, use level order triversal ArrayList<TreeNode> q = new ArrayList<TreeNode>(); q.add(root); int depth = 0; while(!q.isEmpty()) { ArrayList<TreeNode> next = new ArrayList<TreeNode>(); for(TreeNode node : q) { if(node.left != null) next.add(node.left); if(node.right != null) next.add(node.right); } q = new ArrayList<TreeNode>(next); depth++; } return depth; } }
good blog, how was your interview?
ReplyDeleteHello,
ReplyDeleteI have tried your recursive solution in the leetcode, but instead of the depth + 1, I have used depth++ or ++depth, but the tests are failing and I do not understand why neither of them are equivalent.