binary-tree-level-order-traversal

Author: byol-han

binary-tree-level-order-traversal/byol-han.js

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+/**
+ * https://leetcode.com/problems/binary-tree-level-order-traversal/description/
+ * 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) {
+  const result = [];
+  if (!root) return result;
+
+  const queue = [root];
+
+  while (queue.length > 0) {
+    const levelSize = queue.length;
+    const level = [];
+
+    for (let i = 0; i < levelSize; i++) {
+      const node = queue.shift();
+      level.push(node.val);
+
+      if (node.left) queue.push(node.left);
+      if (node.right) queue.push(node.right);
+    }
+
+    result.push(level);
+  }
+
+  return result;
+};