solve: binary tree level order traversal

Author: sounmind

binary-tree-level-order-traversal/evan.js

@@ -0,0 +1,37 @@
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var levelOrder = function (root) {
+  const result = [];
+
+  const dfs = (node, level) => {
+    if (!node) {
+      return;
+    }
+
+    if (!result[level]) {
+      result[level] = [];
+    }
+
+    result[level].push(node.val);
+
+    dfs(node.left, level + 1);
+    dfs(node.right, level + 1);
+  };
+
+  dfs(root, 0);
+
+  return result;
+};
+
+/**
+ * Time Complexity: O(n)
+ * - The function visits each node exactly once, making it O(n).
+ * - Here, n is the number of nodes in the binary tree.
+ *
+ * Space Complexity: O(n)
+ * - The space complexity is determined by the recursion stack.
+ * - In the worst case, the recursion stack could store all nodes in the binary tree.
+ * - Thus, the space complexity is O(n).
+ */