feat(soobing): binary-tree-level-order-traversal

Author: soobing

binary-tree-level-order-traversal/soobing.ts

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+/**
+ * 문제 설명
+ * - 이진 트리의 레벨 순서 순회 문제
+ *
+ * 아이디어
+ * 1) BFS 레벨 순서별로 큐에 넣어서 탐색하며 결과를 반환
+ *
+ */
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+function levelOrder(root: TreeNode | null): number[][] {
+  if (!root) return [];
+
+  const queue: TreeNode[] = [root];
+  const result: number[][] = [];
+
+  while (queue.length) {
+    const levelSize = queue.length;
+    const currentLevel: number[] = [];
+    for (let i = 0; i < levelSize; i++) {
+      const node = queue.shift()!;
+      currentLevel.push(node.val);
+
+      if (node.left) queue.push(node.left);
+      if (node.right) queue.push(node.right);
+    }
+
+    result.push(currentLevel);
+  }
+  return result;
+}