Solution for Maximum Depth of Binary Tree #227

Refactor maxDepth method and simplify dfs parameters for clarity

Author: dohyeon2

maximum-depth-of-binary-tree/dohyeon2.java

@@ -0,0 +1,40 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ * int val;
+ * TreeNode left;
+ * TreeNode right;
+ * TreeNode() {}
+ * TreeNode(int val) { this.val = val; }
+ * TreeNode(int val, TreeNode left, TreeNode right) {
+ * this.val = val;
+ * this.left = left;
+ * this.right = right;
+ * }
+ * }
+ */
+
+// Good solution from Leetcode
+// class Solution{
+// public int maxDepth(TreeNode root){
+// if (root==null) return 0;
+// return Math.max(maxDepth(root.left),maxDepth(root.right)) + 1;
+// }
+// }
+
+class Solution {
+    // TC : O(n)
+    // SC : O(h) height of tree(DFS), width of tree(BFS)
+    public int maxDepth(TreeNode root) {
+        return dfs(root, 0);
+    }
+
+    private int dfs(TreeNode cursor, int depth) {
+        if (cursor == null) {
+            return depth;
+        }
+        return Math.max(
+                dfs(cursor.left, depth + 1),
+                dfs(cursor.right, depth + 1));
+    }
+}