feat: add Swift codes for iteration_and_recursion article (#717)

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nuomi1 2023-09-02 19:47:18 +08:00 committed by GitHub
parent 620bfb1f1d
commit fd84d4443e
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3 changed files with 136 additions and 0 deletions

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@ -6,6 +6,8 @@ let package = Package(
name: "HelloAlgo",
products: [
// chapter_computational_complexity
.executable(name: "iteration", targets: ["iteration"]),
.executable(name: "recursion", targets: ["recursion"]),
.executable(name: "time_complexity", targets: ["time_complexity"]),
.executable(name: "worst_best_time_complexity", targets: ["worst_best_time_complexity"]),
.executable(name: "space_complexity", targets: ["space_complexity"]),
@ -94,6 +96,8 @@ let package = Package(
.target(name: "graph_adjacency_list_target", dependencies: ["utils"], path: "chapter_graph", sources: ["graph_adjacency_list_target.swift"], swiftSettings: [.define("TARGET")]),
.target(name: "binary_search_insertion_target", path: "chapter_searching", sources: ["binary_search_insertion_target.swift"], swiftSettings: [.define("TARGET")]),
// chapter_computational_complexity
.executableTarget(name: "iteration", path: "chapter_computational_complexity", sources: ["iteration.swift"]),
.executableTarget(name: "recursion", path: "chapter_computational_complexity", sources: ["recursion.swift"]),
.executableTarget(name: "time_complexity", path: "chapter_computational_complexity", sources: ["time_complexity.swift"]),
.executableTarget(name: "worst_best_time_complexity", path: "chapter_computational_complexity", sources: ["worst_best_time_complexity.swift"]),
.executableTarget(name: "space_complexity", dependencies: ["utils"], path: "chapter_computational_complexity", sources: ["space_complexity.swift"]),

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@ -0,0 +1,75 @@
/**
* File: iteration.swift
* Created Time: 2023-09-02
* Author: nuomi1 (nuomi1@qq.com)
*/
/* for */
func forLoop(n: Int) -> Int {
var res = 0
// 1, 2, ..., n-1, n
for i in 1 ... n {
res += i
}
return res
}
/* while */
func whileLoop(n: Int) -> Int {
var res = 0
var i = 1 //
// 1, 2, ..., n-1, n
while i <= n {
res += i
i += 1 //
}
return res
}
/* while */
func whileLoopII(n: Int) -> Int {
var res = 0
var i = 1 //
// 1, 4, ...
while i <= n {
res += i
//
i += 1
i *= 2
}
return res
}
/* for */
func nestedForLoop(n: Int) -> String {
var res = ""
// i = 1, 2, ..., n-1, n
for i in 1 ... n {
// j = 1, 2, ..., n-1, n
for j in 1 ... n {
res.append("(\(i), \(j)), ")
}
}
return res
}
@main
enum Iteration {
/* Driver Code */
static func main() {
let n = 5
var res = 0
res = forLoop(n: n)
print("\nfor 循环的求和结果 res = \(res)")
res = whileLoop(n: n)
print("\nwhile 循环的求和结果 res = \(res)")
res = whileLoopII(n: n)
print("\nwhile 循环(两次更新)求和结果 res = \(res)")
let resStr = nestedForLoop(n: n)
print("\n双层 for 循环的遍历结果 \(resStr)")
}
}

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@ -0,0 +1,57 @@
/**
* File: recursion.swift
* Created Time: 2023-09-02
* Author: nuomi1 (nuomi1@qq.com)
*/
/* */
func recur(n: Int) -> Int {
//
if n == 1 {
return 1
}
//
let res = recur(n: n - 1)
//
return n + res
}
/* */
func tailRecur(n: Int, res: Int) -> Int {
//
if n == 0 {
return res
}
//
return tailRecur(n: n - 1, res: res + n)
}
/* */
func fib(n: Int) -> Int {
// f(1) = 0, f(2) = 1
if n == 1 || n == 2 {
return n - 1
}
// f(n) = f(n-1) + f(n-2)
let res = fib(n: n - 1) + fib(n: n - 2)
// f(n)
return res
}
@main
enum Recursion {
/* Driver Code */
static func main() {
let n = 5
var res = 0
res = recursion.recur(n: n)
print("\n递归函数的求和结果 res = \(res)")
res = recursion.tailRecur(n: n, res: 0)
print("\n尾递归函数的求和结果 res = \(res)")
res = recursion.fib(n: n)
print("\n斐波那契数列的第 \(n) 项为 \(res)")
}
}