feat: add swift implementation to lcci problem: No.16.24 (#2766)

Author: klever34

lcci/16.24.Pairs With Sum/README.md

@@ -126,6 +126,29 @@ function pairSums(nums: number[], target: number): number[][] {
 }
 ```
 
+```swift
+class Solution {
+    func pairSums(_ nums: [Int], _ target: Int) -> [[Int]] {
+        var countMap = [Int: Int]()
+        var ans = [[Int]]()
+
+        for x in nums {
+            let y = target - x
+            if let yCount = countMap[y], yCount > 0 {
+                ans.append([x, y])
+                countMap[y] = yCount - 1
+                if countMap[y] == 0 {
+                    countMap.removeValue(forKey: y)
+                }
+            } else {
+                countMap[x, default: 0] += 1
+            }
+        }
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.24.Pairs With Sum/README_EN.md

@@ -130,6 +130,29 @@ function pairSums(nums: number[], target: number): number[][] {
 }
 ```
 
+```swift
+class Solution {
+    func pairSums(_ nums: [Int], _ target: Int) -> [[Int]] {
+        var countMap = [Int: Int]()
+        var ans = [[Int]]()
+
+        for x in nums {
+            let y = target - x
+            if let yCount = countMap[y], yCount > 0 {
+                ans.append([x, y])
+                countMap[y] = yCount - 1
+                if countMap[y] == 0 {
+                    countMap.removeValue(forKey: y)
+                }
+            } else {
+                countMap[x, default: 0] += 1
+            }
+        }
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.24.Pairs With Sum/Solution.swift

@@ -0,0 +1,20 @@
+class Solution {
+    func pairSums(_ nums: [Int], _ target: Int) -> [[Int]] {
+        var countMap = [Int: Int]()
+        var ans = [[Int]]()
+        
+        for x in nums {
+            let y = target - x
+            if let yCount = countMap[y], yCount > 0 {
+                ans.append([x, y])
+                countMap[y] = yCount - 1
+                if countMap[y] == 0 {
+                    countMap.removeValue(forKey: y)
+                }
+            } else {
+                countMap[x, default: 0] += 1
+            }
+        }
+        return ans
+    }
+}