hello-algo/codes/swift/chapter_tree/array_binary_tree.swift

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/**
* File: array_binary_tree.swift
* Created Time: 2023-07-23
* Author: nuomi1 (nuomi1@qq.com)
*/
import utils
/* */
class ArrayBinaryTree {
private var tree: [Int?]
/* */
init(arr: [Int?]) {
tree = arr
}
/* */
func size() -> Int {
tree.count
}
/* i */
func val(i: Int) -> Int? {
// null
if i < 0 || i >= size() {
return nil
}
return tree[i]
}
/* i */
func left(i: Int) -> Int {
2 * i + 1
}
/* i */
func right(i: Int) -> Int {
2 * i + 2
}
/* i */
func parent(i: Int) -> Int {
(i - 1) / 2
}
/* */
func levelOrder() -> [Int] {
var res: [Int] = []
//
for i in stride(from: 0, to: size(), by: 1) {
if let val = val(i: i) {
res.append(val)
}
}
return res
}
/* */
private func dfs(i: Int, order: String, res: inout [Int]) {
//
guard let val = val(i: i) else {
return
}
//
if order == "pre" {
res.append(val)
}
dfs(i: left(i: i), order: order, res: &res)
//
if order == "in" {
res.append(val)
}
dfs(i: right(i: i), order: order, res: &res)
//
if order == "post" {
res.append(val)
}
}
/* */
func preOrder() -> [Int] {
var res: [Int] = []
dfs(i: 0, order: "pre", res: &res)
return res
}
/* */
func inOrder() -> [Int] {
var res: [Int] = []
dfs(i: 0, order: "in", res: &res)
return res
}
/* */
func postOrder() -> [Int] {
var res: [Int] = []
dfs(i: 0, order: "post", res: &res)
return res
}
}
@main
enum _ArrayBinaryTree {
/* Driver Code */
static func main() {
//
//
let arr = [1, 2, 3, 4, nil, 6, 7, 8, 9, nil, nil, 12, nil, nil, 15]
let root = TreeNode.listToTree(arr: arr)
print("\n初始化二叉树\n")
print("二叉树的数组表示:")
print(arr)
print("二叉树的链表表示:")
PrintUtil.printTree(root: root)
//
let abt = ArrayBinaryTree(arr: arr)
// 访
let i = 1
let l = abt.left(i: i)
let r = abt.right(i: i)
let p = abt.parent(i: i)
print("\n当前节点的索引为 \(i) ,值为 \(abt.val(i: i) as Any)")
print("其左子节点的索引为 \(l) ,值为 \(abt.val(i: l) as Any)")
print("其右子节点的索引为 \(r) ,值为 \(abt.val(i: r) as Any)")
print("其父节点的索引为 \(p) ,值为 \(abt.val(i: p) as Any)")
//
var res = abt.levelOrder()
print("\n层序遍历为:\(res)")
res = abt.preOrder()
print("前序遍历为:\(res)")
res = abt.inOrder()
print("中序遍历为:\(res)")
res = abt.postOrder()
print("后序遍历为:\(res)")
}
}