Review Swift codes (#1150)

* feat(swift): review for chapter_computational_complexity

* feat(swift): review for chapter_data_structure

* feat(swift): review for chapter_array_and_linkedlist

* feat(swift): review for chapter_stack_and_queue

* feat(swift): review for chapter_hashing

* feat(swift): review for chapter_tree

* feat(swift): add codes for heap article

* feat(swift): review for chapter_heap

* feat(swift): review for chapter_graph

* feat(swift): review for chapter_searching

* feat(swift): review for chapter_sorting

* feat(swift): review for chapter_divide_and_conquer

* feat(swift): review for chapter_backtracking

* feat(swift): review for chapter_dynamic_programming

* feat(swift): review for chapter_greedy

* feat(swift): review for utils

* feat(swift): update ci tool

* feat(swift): trailing closure

* feat(swift): array init

* feat(swift): map index

.github/workflows/swift.yml

@@ -19,9 +19,9 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
-        swift: ["5.9", "5.8.1", "5.7.3"]
+        swift: ["5.10", "5.9", "5.8"]
     steps:
-      - uses: swift-actions/setup-swift@v1
+      - uses: swift-actions/setup-swift@v2
         with:
           swift-version: ${{ matrix.swift }}
       - uses: actions/checkout@v4

codes/swift/Package.swift

@@ -41,6 +41,7 @@ let package = Package(
         .executable(name: "binary_search_tree", targets: ["binary_search_tree"]),
         .executable(name: "avl_tree", targets: ["avl_tree"]),
         // chapter_heap
+        .executable(name: "heap", targets: ["heap"]),
         .executable(name: "my_heap", targets: ["my_heap"]),
         .executable(name: "top_k", targets: ["top_k"]),
         // chapter_graph
@@ -143,6 +144,7 @@ let package = Package(
         .executableTarget(name: "binary_search_tree", dependencies: ["utils"], path: "chapter_tree", sources: ["binary_search_tree.swift"]),
         .executableTarget(name: "avl_tree", dependencies: ["utils"], path: "chapter_tree", sources: ["avl_tree.swift"]),
         // chapter_heap
+        .executableTarget(name: "heap", dependencies: ["utils", .product(name: "HeapModule", package: "swift-collections")], path: "chapter_heap", sources: ["heap.swift"]),
         .executableTarget(name: "my_heap", dependencies: ["utils"], path: "chapter_heap", sources: ["my_heap.swift"]),
         .executableTarget(name: "top_k", dependencies: ["utils", .product(name: "HeapModule", package: "swift-collections")], path: "chapter_heap", sources: ["top_k.swift"]),
         // chapter_graph

codes/swift/chapter_array_and_linkedlist/array.swift

@@ -54,6 +54,11 @@ func traverse(nums: [Int]) {
     for num in nums {
         count += num
     }
+    // 同时遍历数据索引和元素
+    for (i, num) in nums.enumerated() {
+        count += nums[i]
+        count += num
+    }
 }
 
 /* 在数组中查找指定元素 */

codes/swift/chapter_array_and_linkedlist/linked_list.swift

@@ -22,7 +22,6 @@ func remove(n0: ListNode) {
     let P = n0.next
     let n1 = P?.next
     n0.next = n1
-    P?.next = nil
 }
 
 /* 访问链表中索引为 index 的节点 */

codes/swift/chapter_array_and_linkedlist/my_list.swift

@@ -7,12 +7,15 @@
 /* 列表类 */
 class MyList {
     private var arr: [Int] // 数组（存储列表元素）
-    private var _capacity = 10 // 列表容量
-    private var _size = 0 // 列表长度（当前元素数量）
-    private let extendRatio = 2 // 每次列表扩容的倍数
+    private var _capacity: Int // 列表容量
+    private var _size: Int // 列表长度（当前元素数量）
+    private let extendRatio: Int // 每次列表扩容的倍数
 
     /* 构造方法 */
     init() {
+        _capacity = 10
+        _size = 0
+        extendRatio = 2
         arr = Array(repeating: 0, count: _capacity)
     }
 
@@ -29,15 +32,15 @@ class MyList {
     /* 访问元素 */
     func get(index: Int) -> Int {
         // 索引如果越界则抛出错误，下同
-        if index < 0 || index >= _size {
+        if index < 0 || index >= size() {
             fatalError("索引越界")
         }
         return arr[index]
     }
 
     /* 更新元素 */
     func set(index: Int, num: Int) {
-        if index < 0 || index >= _size {
+        if index < 0 || index >= size() {
             fatalError("索引越界")
         }
         arr[index] = num
@@ -46,25 +49,25 @@ class MyList {
     /* 在尾部添加元素 */
     func add(num: Int) {
         // 元素数量超出容量时，触发扩容机制
-        if _size == _capacity {
+        if size() == capacity() {
             extendCapacity()
         }
-        arr[_size] = num
+        arr[size()] = num
         // 更新元素数量
         _size += 1
     }
 
     /* 在中间插入元素 */
     func insert(index: Int, num: Int) {
-        if index < 0 || index >= _size {
+        if index < 0 || index >= size() {
             fatalError("索引越界")
         }
         // 元素数量超出容量时，触发扩容机制
-        if _size == _capacity {
+        if size() == capacity() {
             extendCapacity()
         }
         // 将索引 index 以及之后的元素都向后移动一位
-        for j in sequence(first: _size - 1, next: { $0 >= index + 1 ? $0 - 1 : nil }) {
+        for j in (index ..< size()).reversed() {
             arr[j + 1] = arr[j]
         }
         arr[index] = num
@@ -75,12 +78,12 @@ class MyList {
     /* 删除元素 */
     @discardableResult
     func remove(index: Int) -> Int {
-        if index < 0 || index >= _size {
+        if index < 0 || index >= size() {
             fatalError("索引越界")
         }
         let num = arr[index]
         // 将将索引 index 之后的元素都向前移动一位
-        for j in index ..< (_size - 1) {
+        for j in index ..< (size() - 1) {
             arr[j] = arr[j + 1]
         }
         // 更新元素数量
@@ -92,18 +95,14 @@ class MyList {
     /* 列表扩容 */
     func extendCapacity() {
         // 新建一个长度为原数组 extendRatio 倍的新数组，并将原数组复制到新数组
-        arr = arr + Array(repeating: 0, count: _capacity * (extendRatio - 1))
+        arr = arr + Array(repeating: 0, count: capacity() * (extendRatio - 1))
         // 更新列表容量
         _capacity = arr.count
     }
 
     /* 将列表转换为数组 */
     func toArray() -> [Int] {
-        var arr = Array(repeating: 0, count: _size)
-        for i in 0 ..< _size {
-            arr[i] = get(index: i)
-        }
-        return arr
+        Array(arr.prefix(size()))
     }
 }
 

codes/swift/chapter_backtracking/subset_sum_i.swift

@@ -13,7 +13,7 @@ func backtrack(state: inout [Int], target: Int, choices: [Int], start: Int, res:
     }
     // 遍历所有选择
     // 剪枝二：从 start 开始遍历，避免生成重复子集
-    for i in stride(from: start, to: choices.count, by: 1) {
+    for i in choices.indices.dropFirst(start) {
         // 剪枝一：若子集和超过 target ，则直接结束循环
         // 这是因为数组已排序，后边元素更大，子集和一定超过 target
         if target - choices[i] < 0 {

codes/swift/chapter_backtracking/subset_sum_i_naive.swift

@@ -12,7 +12,7 @@ func backtrack(state: inout [Int], target: Int, total: Int, choices: [Int], res:
         return
     }
     // 遍历所有选择
-    for i in stride(from: 0, to: choices.count, by: 1) {
+    for i in choices.indices {
         // 剪枝：若子集和超过 target ，则跳过该选择
         if total + choices[i] > target {
             continue

codes/swift/chapter_backtracking/subset_sum_ii.swift

@@ -14,7 +14,7 @@ func backtrack(state: inout [Int], target: Int, choices: [Int], start: Int, res:
     // 遍历所有选择
     // 剪枝二：从 start 开始遍历，避免生成重复子集
     // 剪枝三：从 start 开始遍历，避免重复选择同一元素
-    for i in stride(from: start, to: choices.count, by: 1) {
+    for i in choices.indices.dropFirst(start) {
         // 剪枝一：若子集和超过 target ，则直接结束循环
         // 这是因为数组已排序，后边元素更大，子集和一定超过 target
         if target - choices[i] < 0 {

codes/swift/chapter_computational_complexity/recursion.swift

@@ -22,7 +22,7 @@ func forLoopRecur(n: Int) -> Int {
     var stack: [Int] = []
     var res = 0
     // 递：递归调用
-    for i in stride(from: n, to: 0, by: -1) {
+    for i in (1 ... n).reversed() {
         // 通过“入栈操作”模拟“递”
         stack.append(i)
     }

codes/swift/chapter_computational_complexity/time_complexity.swift

@@ -49,7 +49,7 @@ func quadratic(n: Int) -> Int {
 func bubbleSort(nums: inout [Int]) -> Int {
     var count = 0 // 计数器
     // 外循环：未排序区间为 [0, i]
-    for i in stride(from: nums.count - 1, to: 0, by: -1) {
+    for i in nums.indices.dropFirst().reversed() {
         // 内循环：将未排序区间 [0, i] 中的最大元素交换至该区间的最右端
         for j in 0 ..< i {
             if nums[j] > nums[j + 1] {

codes/swift/chapter_divide_and_conquer/binary_search_recur.swift

@@ -26,9 +26,8 @@ func dfs(nums: [Int], target: Int, i: Int, j: Int) -> Int {
 
 /* 二分查找 */
 func binarySearch(nums: [Int], target: Int) -> Int {
-    let n = nums.count
     // 求解问题 f(0, n-1)
-    return dfs(nums: nums, target: target, i: 0, j: n - 1)
+    dfs(nums: nums, target: target, i: nums.startIndex, j: nums.endIndex - 1)
 }
 
 @main

codes/swift/chapter_divide_and_conquer/build_tree.swift

@@ -28,7 +28,7 @@ func dfs(preorder: [Int], inorderMap: [Int: Int], i: Int, l: Int, r: Int) -> Tre
 func buildTree(preorder: [Int], inorder: [Int]) -> TreeNode? {
     // 初始化哈希表，存储 inorder 元素到索引的映射
     let inorderMap = inorder.enumerated().reduce(into: [:]) { $0[$1.element] = $1.offset }
-    return dfs(preorder: preorder, inorderMap: inorderMap, i: 0, l: 0, r: inorder.count - 1)
+    return dfs(preorder: preorder, inorderMap: inorderMap, i: inorder.startIndex, l: inorder.startIndex, r: inorder.endIndex - 1)
 }
 
 @main

codes/swift/chapter_dynamic_programming/climbing_stairs_constraint_dp.swift

@@ -17,7 +17,7 @@ func climbingStairsConstraintDP(n: Int) -> Int {
     dp[2][1] = 0
     dp[2][2] = 1
     // 状态转移：从较小子问题逐步求解较大子问题
-    for i in stride(from: 3, through: n, by: 1) {
+    for i in 3 ... n {
         dp[i][1] = dp[i - 1][2]
         dp[i][2] = dp[i - 2][1] + dp[i - 2][2]
     }

codes/swift/chapter_dynamic_programming/climbing_stairs_dp.swift

@@ -15,7 +15,7 @@ func climbingStairsDP(n: Int) -> Int {
     dp[1] = 1
     dp[2] = 2
     // 状态转移：从较小子问题逐步求解较大子问题
-    for i in stride(from: 3, through: n, by: 1) {
+    for i in 3 ... n {
         dp[i] = dp[i - 1] + dp[i - 2]
     }
     return dp[n]
@@ -28,7 +28,7 @@ func climbingStairsDPComp(n: Int) -> Int {
     }
     var a = 1
     var b = 2
-    for _ in stride(from: 3, through: n, by: 1) {
+    for _ in 3 ... n {
         (a, b) = (b, a + b)
     }
     return b

codes/swift/chapter_dynamic_programming/coin_change.swift

@@ -11,12 +11,12 @@ func coinChangeDP(coins: [Int], amt: Int) -> Int {
     // 初始化 dp 表
     var dp = Array(repeating: Array(repeating: 0, count: amt + 1), count: n + 1)
     // 状态转移：首行首列
-    for a in stride(from: 1, through: amt, by: 1) {
+    for a in 1 ... amt {
         dp[0][a] = MAX
     }
     // 状态转移：其余行和列
-    for i in stride(from: 1, through: n, by: 1) {
-        for a in stride(from: 1, through: amt, by: 1) {
+    for i in 1 ... n {
+        for a in 1 ... amt {
             if coins[i - 1] > a {
                 // 若超过目标金额，则不选硬币 i
                 dp[i][a] = dp[i - 1][a]
@@ -37,8 +37,8 @@ func coinChangeDPComp(coins: [Int], amt: Int) -> Int {
     var dp = Array(repeating: MAX, count: amt + 1)
     dp[0] = 0
     // 状态转移
-    for i in stride(from: 1, through: n, by: 1) {
-        for a in stride(from: 1, through: amt, by: 1) {
+    for i in 1 ... n {
+        for a in 1 ... amt {
             if coins[i - 1] > a {
                 // 若超过目标金额，则不选硬币 i
                 dp[a] = dp[a]

codes/swift/chapter_dynamic_programming/coin_change_ii.swift

@@ -10,12 +10,12 @@ func coinChangeIIDP(coins: [Int], amt: Int) -> Int {
     // 初始化 dp 表
     var dp = Array(repeating: Array(repeating: 0, count: amt + 1), count: n + 1)
     // 初始化首列
-    for i in stride(from: 0, through: n, by: 1) {
+    for i in 0 ... n {
         dp[i][0] = 1
     }
     // 状态转移
-    for i in stride(from: 1, through: n, by: 1) {
-        for a in stride(from: 1, through: amt, by: 1) {
+    for i in 1 ... n {
+        for a in 1 ... amt {
             if coins[i - 1] > a {
                 // 若超过目标金额，则不选硬币 i
                 dp[i][a] = dp[i - 1][a]
@@ -35,8 +35,8 @@ func coinChangeIIDPComp(coins: [Int], amt: Int) -> Int {
     var dp = Array(repeating: 0, count: amt + 1)
     dp[0] = 1
     // 状态转移
-    for i in stride(from: 1, through: n, by: 1) {
-        for a in stride(from: 1, through: amt, by: 1) {
+    for i in 1 ... n {
+        for a in 1 ... amt {
             if coins[i - 1] > a {
                 // 若超过目标金额，则不选硬币 i
                 dp[a] = dp[a]

codes/swift/chapter_dynamic_programming/edit_distance.swift

@@ -67,15 +67,15 @@ func editDistanceDP(s: String, t: String) -> Int {
     let m = t.utf8CString.count
     var dp = Array(repeating: Array(repeating: 0, count: m + 1), count: n + 1)
     // 状态转移：首行首列
-    for i in stride(from: 1, through: n, by: 1) {
+    for i in 1 ... n {
         dp[i][0] = i
     }
-    for j in stride(from: 1, through: m, by: 1) {
+    for j in 1 ... m {
         dp[0][j] = j
     }
     // 状态转移：其余行和列
-    for i in stride(from: 1, through: n, by: 1) {
-        for j in stride(from: 1, through: m, by: 1) {
+    for i in 1 ... n {
+        for j in 1 ... m {
             if s.utf8CString[i - 1] == t.utf8CString[j - 1] {
                 // 若两字符相等，则直接跳过此两字符
                 dp[i][j] = dp[i - 1][j - 1]
@@ -94,16 +94,16 @@ func editDistanceDPComp(s: String, t: String) -> Int {
     let m = t.utf8CString.count
     var dp = Array(repeating: 0, count: m + 1)
     // 状态转移：首行
-    for j in stride(from: 1, through: m, by: 1) {
+    for j in 1 ... m {
         dp[j] = j
     }
     // 状态转移：其余行
-    for i in stride(from: 1, through: n, by: 1) {
+    for i in 1 ... n {
         // 状态转移：首列
         var leftup = dp[0] // 暂存 dp[i-1, j-1]
         dp[0] = i
         // 状态转移：其余列
-        for j in stride(from: 1, through: m, by: 1) {
+        for j in 1 ... m {
             let temp = dp[j]
             if s.utf8CString[i - 1] == t.utf8CString[j - 1] {
                 // 若两字符相等，则直接跳过此两字符

codes/swift/chapter_dynamic_programming/knapsack.swift

@@ -49,8 +49,8 @@ func knapsackDP(wgt: [Int], val: [Int], cap: Int) -> Int {
     // 初始化 dp 表
     var dp = Array(repeating: Array(repeating: 0, count: cap + 1), count: n + 1)
     // 状态转移
-    for i in stride(from: 1, through: n, by: 1) {
-        for c in stride(from: 1, through: cap, by: 1) {
+    for i in 1 ... n {
+        for c in 1 ... cap {
             if wgt[i - 1] > c {
                 // 若超过背包容量，则不选物品 i
                 dp[i][c] = dp[i - 1][c]
@@ -69,9 +69,9 @@ func knapsackDPComp(wgt: [Int], val: [Int], cap: Int) -> Int {
     // 初始化 dp 表
     var dp = Array(repeating: 0, count: cap + 1)
     // 状态转移
-    for i in stride(from: 1, through: n, by: 1) {
+    for i in 1 ... n {
         // 倒序遍历
-        for c in stride(from: cap, through: 1, by: -1) {
+        for c in (1 ... cap).reversed() {
             if wgt[i - 1] <= c {
                 // 不选和选物品 i 这两种方案的较大值
                 dp[c] = max(dp[c], dp[c - wgt[i - 1]] + val[i - 1])

codes/swift/chapter_dynamic_programming/min_cost_climbing_stairs_dp.swift

@@ -16,7 +16,7 @@ func minCostClimbingStairsDP(cost: [Int]) -> Int {
     dp[1] = cost[1]
     dp[2] = cost[2]
     // 状态转移：从较小子问题逐步求解较大子问题
-    for i in stride(from: 3, through: n, by: 1) {
+    for i in 3 ... n {
         dp[i] = min(dp[i - 1], dp[i - 2]) + cost[i]
     }
     return dp[n]
@@ -29,7 +29,7 @@ func minCostClimbingStairsDPComp(cost: [Int]) -> Int {
         return cost[n]
     }
     var (a, b) = (cost[1], cost[2])
-    for i in stride(from: 3, through: n, by: 1) {
+    for i in 3 ... n {
         (a, b) = (b, min(a, b) + cost[i])
     }
     return b