99 lines
2.3 KiB
Swift
99 lines
2.3 KiB
Swift
/**
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* File: space_complexity.swift
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* Created Time: 2023-01-01
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import utils
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/* Function */
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@discardableResult
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func function() -> Int {
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// Perform some operations
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return 0
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}
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/* Constant complexity */
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func constant(n: Int) {
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// Constants, variables, objects occupy O(1) space
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let a = 0
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var b = 0
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let nums = Array(repeating: 0, count: 10000)
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let node = ListNode(x: 0)
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// Variables in a loop occupy O(1) space
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for _ in 0 ..< n {
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let c = 0
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}
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// Functions in a loop occupy O(1) space
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for _ in 0 ..< n {
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function()
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}
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}
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/* Linear complexity */
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func linear(n: Int) {
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// Array of length n occupies O(n) space
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let nums = Array(repeating: 0, count: n)
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// A list of length n occupies O(n) space
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let nodes = (0 ..< n).map { ListNode(x: $0) }
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// A hash table of length n occupies O(n) space
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let map = Dictionary(uniqueKeysWithValues: (0 ..< n).map { ($0, "\($0)") })
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}
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/* Linear complexity (recursive implementation) */
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func linearRecur(n: Int) {
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print("Recursion n = \(n)")
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if n == 1 {
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return
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}
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linearRecur(n: n - 1)
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}
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/* Quadratic complexity */
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func quadratic(n: Int) {
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// A two-dimensional list occupies O(n^2) space
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let numList = Array(repeating: Array(repeating: 0, count: n), count: n)
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}
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/* Quadratic complexity (recursive implementation) */
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@discardableResult
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func quadraticRecur(n: Int) -> Int {
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if n <= 0 {
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return 0
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}
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// Array nums length = n, n-1, ..., 2, 1
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let nums = Array(repeating: 0, count: n)
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print("Recursion n = \(n) with nums length = \(nums.count)")
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return quadraticRecur(n: n - 1)
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}
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/* Exponential complexity (building a full binary tree) */
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func buildTree(n: Int) -> TreeNode? {
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if n == 0 {
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return nil
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}
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let root = TreeNode(x: 0)
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root.left = buildTree(n: n - 1)
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root.right = buildTree(n: n - 1)
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return root
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}
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@main
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enum SpaceComplexity {
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/* Driver Code */
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static func main() {
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let n = 5
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// Constant complexity
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constant(n: n)
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// Linear complexity
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linear(n: n)
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linearRecur(n: n)
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// Quadratic complexity
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quadratic(n: n)
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quadraticRecur(n: n)
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// Exponential complexity
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let root = buildTree(n: n)
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PrintUtil.printTree(root: root)
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}
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}
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