feat: add swift implementation to lcp problem: No.62 (#3972)

Author: klever34

lcp/LCP 62. 交通枢纽/README.md

@@ -205,6 +205,41 @@ function transportationHub(path: number[][]): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func transportationHub(_ path: [[Int]]) -> Int {
+        var inDegree = [Int: Int]()
+        var outDegree = [Int: Int]()
+        var nodeSet = Set<Int>()
+        var visitedEdges = Set<String>()
+
+        for p in path {
+            let a = p[0]
+            let b = p[1]
+            let edgeKey = "\(a)-\(b)"
+
+            if !visitedEdges.contains(edgeKey) {
+                visitedEdges.insert(edgeKey)
+                nodeSet.insert(a)
+                nodeSet.insert(b)
+                inDegree[b, default: 0] += 1
+                outDegree[a, default: 0] += 1
+            }
+        }
+
+        for node in nodeSet {
+            if inDegree[node, default: 0] == nodeSet.count - 1 && outDegree[node, default: 0] == 0 {
+                return node
+            }
+        }
+
+        return -1
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcp/LCP 62. 交通枢纽/Solution.swift

@@ -0,0 +1,30 @@
+class Solution {
+    func transportationHub(_ path: [[Int]]) -> Int {
+        var inDegree = [Int: Int]()
+        var outDegree = [Int: Int]()
+        var nodeSet = Set<Int>()
+        var visitedEdges = Set<String>()
+
+        for p in path {
+            let a = p[0]
+            let b = p[1]
+            let edgeKey = "\(a)-\(b)"
+
+            if !visitedEdges.contains(edgeKey) {
+                visitedEdges.insert(edgeKey)
+                nodeSet.insert(a)
+                nodeSet.insert(b)
+                inDegree[b, default: 0] += 1
+                outDegree[a, default: 0] += 1
+            }
+        }
+
+        for node in nodeSet {
+            if inDegree[node, default: 0] == nodeSet.count - 1 && outDegree[node, default: 0] == 0 {
+                return node
+            }
+        }
+
+        return -1
+    }
+}