All files / leetCode 0107.ts

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
 
 
 
 
3x
 
3x
1x
 
2x
 
2x
4x
4x
 
4x
6x
6x
6x
2x
6x
2x
 
 
4x
 
 
2x
 
 
import type { TreeNode } from './Tree'
 
export default function levelOrderBottom(
  root: TreeNode<number> | null,
): number[][] {
  const res: number[][] = []
 
  if (root === null)
    return res
 
  const queue = [root]
 
  while (queue.length > 0) {
    const len = queue.length
    const row: number[] = []
 
    for (let i = 0; i < len; i++) {
      const node = queue.shift() as TreeNode<number>
      row.push(node.val)
      if (node.left !== null)
        queue.push(node.left)
      if (node.right !== null)
        queue.push(node.right)
    }
 
    res.unshift(row)
  }
 
  return res
}