feat: add Swift codes for bucket_sort article (#444)

codes/swift/Package.swift

@@ -50,6 +50,7 @@ let package = Package(
         .executable(name: "insertion_sort", targets: ["insertion_sort"]),
         .executable(name: "quick_sort", targets: ["quick_sort"]),
         .executable(name: "merge_sort", targets: ["merge_sort"]),
+        .executable(name: "bucket_sort", targets: ["bucket_sort"]),
         .executable(name: "counting_sort", targets: ["counting_sort"]),
         .executable(name: "radix_sort", targets: ["radix_sort"]),
     ],
@@ -102,6 +103,7 @@ let package = Package(
         .executableTarget(name: "insertion_sort", path: "chapter_sorting", sources: ["insertion_sort.swift"]),
         .executableTarget(name: "quick_sort", path: "chapter_sorting", sources: ["quick_sort.swift"]),
         .executableTarget(name: "merge_sort", path: "chapter_sorting", sources: ["merge_sort.swift"]),
+        .executableTarget(name: "bucket_sort", path: "chapter_sorting", sources: ["bucket_sort.swift"]),
         .executableTarget(name: "counting_sort", path: "chapter_sorting", sources: ["counting_sort.swift"]),
         .executableTarget(name: "radix_sort", path: "chapter_sorting", sources: ["radix_sort.swift"]),
     ]

codes/swift/chapter_sorting/bucket_sort.swift

@@ -0,0 +1,43 @@
+/**
+ * File: bucket_sort.swift
+ * Created Time: 2023-03-27
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+/* 桶排序 */
+func bucketSort(nums: inout [Double]) {
+    // 初始化 k = n/2 个桶，预期向每个桶分配 2 个元素
+    let k = nums.count / 2
+    var buckets = (0 ..< k).map { _ in [Double]() }
+    // 1. 将数组元素分配到各个桶中
+    for num in nums {
+        // 输入数据范围 [0, 1)，使用 num * k 映射到索引范围 [0, k-1]
+        let i = Int(num) * k
+        // 将 num 添加进桶 i
+        buckets[i].append(num)
+    }
+    // 2. 对各个桶执行排序
+    for i in buckets.indices {
+        // 使用内置排序函数，也可以替换成其它排序算法
+        buckets[i].sort()
+    }
+    // 3. 遍历桶合并结果
+    var i = nums.startIndex
+    for bucket in buckets {
+        for num in bucket {
+            nums[i] = num
+            nums.formIndex(after: &i)
+        }
+    }
+}
+
+@main
+enum BucketSort {
+    /* Driver Code */
+    static func main() {
+        // 设输入数据为浮点数，范围为 [0, 1)
+        var nums = [0.49, 0.96, 0.82, 0.09, 0.57, 0.43, 0.91, 0.75, 0.15, 0.37]
+        bucketSort(nums: &nums)
+        print("桶排序完成后 nums = \(nums)")
+    }
+}