hello-algo/codes/swift/chapter_computational_complexity/space_complexity.swift

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/*
* File: space_complexity.swift
* Created Time: 2023-01-01
* Author: nuomi1 (nuomi1@qq.com)
*/
class ListNode {
var val: Int
var next: ListNode?
init(x: Int) {
val = x
}
}
class TreeNode {
var val: Int //
var height: Int //
var left: TreeNode? //
var right: TreeNode? //
init(x: Int) {
val = x
height = 0
}
}
enum PrintUtil {
private class Trunk {
var prev: Trunk?
var str: String
init(prev: Trunk?, str: String) {
self.prev = prev
self.str = str
}
}
static func printTree(root: TreeNode?) {
printTree(root: root, prev: nil, isLeft: false)
}
private static func printTree(root: TreeNode?, prev: Trunk?, isLeft: Bool) {
if root == nil {
return
}
var prevStr = " "
let trunk = Trunk(prev: prev, str: prevStr)
printTree(root: root?.right, prev: trunk, isLeft: true)
if prev == nil {
trunk.str = "———"
} else if isLeft {
trunk.str = "/———"
prevStr = " |"
} else {
trunk.str = "\\———"
prev?.str = prevStr
}
showTrunks(p: trunk)
print(" \(root!.val)")
if prev != nil {
prev?.str = prevStr
}
trunk.str = " |"
printTree(root: root?.left, prev: trunk, isLeft: false)
}
private static func showTrunks(p: Trunk?) {
if p == nil {
return
}
showTrunks(p: p?.prev)
print(p!.str, terminator: "")
}
}
//
@discardableResult
func function() -> Int {
// do something
return 0
}
//
func constant(n: Int) {
// O(1)
let a = 0
var b = 0
let nums = Array(repeating: 0, count: 10000)
let node = ListNode(x: 0)
// O(1)
for _ in 0 ..< n {
let c = 0
}
// O(1)
for _ in 0 ..< n {
function()
}
}
// 线
func linear(n: Int) {
// n O(n)
let nums = Array(repeating: 0, count: n)
// n O(n)
let nodes = (0 ..< n).map { ListNode(x: $0) }
// n O(n)
let map = Dictionary(uniqueKeysWithValues: (0 ..< n).map { ($0, "\($0)") })
}
// 线
func linearRecur(n: Int) {
print("递归 n = \(n)")
if n == 1 {
return
}
linearRecur(n: n - 1)
}
//
func quadratic(n: Int) {
// O(n^2)
let numList = Array(repeating: Array(repeating: 0, count: n), count: n)
}
//
@discardableResult
func quadraticRecur(n: Int) -> Int {
if n <= 0 {
return 0
}
// nums n, n-1, ..., 2, 1
let nums = Array(repeating: 0, count: n)
print("递归 n = \(n) 中的 nums 长度 = \(nums.count)")
return quadraticRecur(n: n - 1)
}
//
func buildTree(n: Int) -> TreeNode? {
if n == 0 {
return nil
}
let root = TreeNode(x: 0)
root.left = buildTree(n: n - 1)
root.right = buildTree(n: n - 1)
return root
}
// Driver Code
func main() {
let n = 5
//
constant(n: n)
// 线
linear(n: n)
linearRecur(n: n)
//
quadratic(n: n)
quadraticRecur(n: n)
//
let root = buildTree(n: n)
PrintUtil.printTree(root: root)
}
main()