binary-tree-level-order-traversal solution

Author: jdy8739

binary-tree-level-order-traversal/jdy8739.js

@@ -0,0 +1,42 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var levelOrder = function (root) {
+    if (!root) {
+        return [];
+    }
+
+    const queue = [root];
+    const answer = [];
+
+    while (queue.length > 0) {
+        const values = [];
+
+        const currentQueueLen = queue.length;
+
+        for (let i = 0; i < currentQueueLen; i++) {
+            const head = queue.shift();
+
+            values.push(head.val);
+
+            head.left && queue.push(head.left);
+            head.right && queue.push(head.right);
+        }
+
+        answer.push(values);
+    }
+
+    return answer;
+};
+
+// 시간복잡도 O(n) -> 모든 노드를 한번씩 너비우선탐색으로 방문하므로
+// 공간복잡도 O(n) -> 큐에 모든 노드의 값을 저장하므로