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| 1 | +import java.util.ArrayDeque |
| 2 | +import java.util.LinkedList |
| 3 | +import java.util.Queue |
| 4 | + |
| 5 | +/** |
| 6 | + * Definition for a binary tree node. |
| 7 | + * class TreeNode(var `val`: Int) { |
| 8 | + * var left: TreeNode? = null |
| 9 | + * var right: TreeNode? = null |
| 10 | + * } |
| 11 | + */ |
| 12 | + |
| 13 | +class Codec { |
| 14 | + // Encodes a URL to a shortened URL. |
| 15 | + fun serialize(root: TreeNode?): String { |
| 16 | + if (root == null) |
| 17 | + return "[]" |
| 18 | + |
| 19 | + val result = mutableListOf<Int?>() |
| 20 | + |
| 21 | + val queue: Queue<TreeNode?> = LinkedList() |
| 22 | + queue += root |
| 23 | + |
| 24 | + var nonNullCount = 1 |
| 25 | + while (queue.isNotEmpty() && nonNullCount > 0) { |
| 26 | + nonNullCount = 0 |
| 27 | + repeat(queue.size) { |
| 28 | + val now = queue.poll() |
| 29 | + |
| 30 | + result += now?.`val` |
| 31 | + |
| 32 | + if (now == null) { |
| 33 | + return@repeat |
| 34 | + } |
| 35 | + |
| 36 | + for (child in arrayOf(now.left, now.right)) { |
| 37 | + queue.add(child) |
| 38 | + if (child != null) |
| 39 | + nonNullCount += 1 |
| 40 | + } |
| 41 | + } |
| 42 | + } |
| 43 | + |
| 44 | + return result.joinToString(",", "[", "]") |
| 45 | + } |
| 46 | + |
| 47 | + // Decodes your encoded data to tree. |
| 48 | + fun deserialize(data: String): TreeNode? { |
| 49 | + if (data == "[]") |
| 50 | + return null |
| 51 | + |
| 52 | + val dataList = data.slice(1 until data.lastIndex) |
| 53 | + .split(',') |
| 54 | + .map { it.toIntOrNull() } |
| 55 | + |
| 56 | + var pointer = 0 |
| 57 | + val root = TreeNode(dataList[pointer++]!!) |
| 58 | + |
| 59 | + val queue: Queue<TreeNode> = ArrayDeque() |
| 60 | + queue += root |
| 61 | + |
| 62 | + while (queue.isNotEmpty() && pointer < dataList.size) { |
| 63 | + val now = queue.poll() |
| 64 | + |
| 65 | + val leftVal = dataList[pointer++] |
| 66 | + val rightVal = dataList[pointer++] |
| 67 | + |
| 68 | + if (leftVal != null) { |
| 69 | + val left = TreeNode(leftVal) |
| 70 | + now.left = left |
| 71 | + queue += left |
| 72 | + } |
| 73 | + |
| 74 | + if (rightVal != null) { |
| 75 | + val right = TreeNode(rightVal) |
| 76 | + now.right = right |
| 77 | + queue += right |
| 78 | + } |
| 79 | + } |
| 80 | + |
| 81 | + return root |
| 82 | + } |
| 83 | +} |
| 84 | + |
| 85 | +/** |
| 86 | + * Your Codec object will be instantiated and called as such: |
| 87 | + * var ser = Codec() |
| 88 | + * var deser = Codec() |
| 89 | + * var data = ser.serialize(longUrl) |
| 90 | + * var ans = deser.deserialize(data) |
| 91 | + */ |
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