mirror of
https://github.com/krahets/hello-algo.git
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e720aa2d24
* Sync recent changes to the revised Word. * Revised the preface chapter * Revised the introduction chapter * Revised the computation complexity chapter * Revised the chapter data structure * Revised the chapter array and linked list * Revised the chapter stack and queue * Revised the chapter hashing * Revised the chapter tree * Revised the chapter heap * Revised the chapter graph * Revised the chapter searching * Reivised the sorting chapter * Revised the divide and conquer chapter * Revised the chapter backtacking * Revised the DP chapter * Revised the greedy chapter * Revised the appendix chapter * Revised the preface chapter doubly * Revised the figures
102 lines
2.7 KiB
Swift
102 lines
2.7 KiB
Swift
/**
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* File: array.swift
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* Created Time: 2023-01-05
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* 随机访问元素 */
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func randomAccess(nums: [Int]) -> Int {
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// 在区间 [0, nums.count) 中随机抽取一个数字
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let randomIndex = nums.indices.randomElement()!
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// 获取并返回随机元素
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let randomNum = nums[randomIndex]
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return randomNum
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}
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/* 扩展数组长度 */
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func extend(nums: [Int], enlarge: Int) -> [Int] {
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// 初始化一个扩展长度后的数组
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var res = Array(repeating: 0, count: nums.count + enlarge)
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// 将原数组中的所有元素复制到新数组
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for i in nums.indices {
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res[i] = nums[i]
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}
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// 返回扩展后的新数组
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return res
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}
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/* 在数组的索引 index 处插入元素 num */
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func insert(nums: inout [Int], num: Int, index: Int) {
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// 把索引 index 以及之后的所有元素向后移动一位
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for i in nums.indices.dropFirst(index).reversed() {
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nums[i] = nums[i - 1]
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}
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// 将 num 赋给 index 处的元素
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nums[index] = num
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}
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/* 删除索引 index 处的元素 */
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func remove(nums: inout [Int], index: Int) {
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// 把索引 index 之后的所有元素向前移动一位
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for i in nums.indices.dropFirst(index).dropLast() {
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nums[i] = nums[i + 1]
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}
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}
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/* 遍历数组 */
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func traverse(nums: [Int]) {
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var count = 0
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// 通过索引遍历数组
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for i in nums.indices {
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count += nums[i]
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}
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// 直接遍历数组元素
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for num in nums {
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count += num
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}
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}
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/* 在数组中查找指定元素 */
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func find(nums: [Int], target: Int) -> Int {
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for i in nums.indices {
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if nums[i] == target {
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return i
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}
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}
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return -1
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}
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@main
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enum _Array {
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/* Driver Code */
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static func main() {
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/* 初始化数组 */
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let arr = Array(repeating: 0, count: 5)
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print("数组 arr = \(arr)")
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var nums = [1, 3, 2, 5, 4]
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print("数组 nums = \(nums)")
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/* 随机访问 */
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let randomNum = randomAccess(nums: nums)
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print("在 nums 中获取随机元素 \(randomNum)")
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/* 长度扩展 */
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nums = extend(nums: nums, enlarge: 3)
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print("将数组长度扩展至 8 ，得到 nums = \(nums)")
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/* 插入元素 */
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insert(nums: &nums, num: 6, index: 3)
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print("在索引 3 处插入数字 6 ，得到 nums = \(nums)")
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/* 删除元素 */
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remove(nums: &nums, index: 2)
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print("删除索引 2 处的元素，得到 nums = \(nums)")
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/* 遍历数组 */
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traverse(nums: nums)
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/* 查找元素 */
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let index = find(nums: nums, target: 3)
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print("在 nums 中查找元素 3 ，得到索引 = \(index)")
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}
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}
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