solve: binary tree level order traversal

Author: wogha95

binary-tree-level-order-traversal/wogha95.js

@@ -1,5 +1,59 @@
+/**
+ * 2차
+ * 각 level의 node 수만큼 끊어서 순회하기
+ *
+ * TC: O(N)
+ * SC: O(N)
+ * N: total of nodes
+ */
+
+/**
+ * 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 result = [];
+  const queue = [root];
+
+  while (queue.length > 0) {
+    const level = queue.length;
+    const currentLevelValList = [];
+
+    for (let i = 0; i < level; i++) {
+      const current = queue.shift();
+
+      currentLevelValList.push(current.val);
+
+      if (current.left) {
+        queue.push(current.left);
+      }
+
+      if (current.right) {
+        queue.push(current.right);
+      }
+    }
+
+    result.push(currentLevelValList);
+  }
+
+  return result;
+};
+
 /**
  * 1차
+ * level과 노드를 queue에 추가해서 정답만들기
  *
  * TC: O(N)
  * SC: O(N)