Create 0684-redundant-connection.swift

swift/0684-redundant-connection.swift

@@ -0,0 +1,54 @@
+/**
+ * Question Link: https://leetcode.com/problems/redundant-connection/
+ */
+
+ class UnionFind {
+    var parents = [Int: Int]()
+    var ranks = [Int: Int]()
+
+    init(n: Int) {
+        for i in 1..<n + 1 {
+            parents[i] = i
+            ranks[i] = 0
+        }
+    }
+
+    func find(n: Int) -> Int {
+        var p = parents[n]!
+        while p != parents[p]! {
+            parents[p] = parents[parents[p]!]
+            p = parents[p]!
+        }
+        return p
+    }
+
+    func union(n1: Int, n2: Int) -> Bool {
+        let p1 = find(n: n1)
+        let p2 = find(n: n2)
+        if p1 == p2 {
+            return false
+        }
+
+        if ranks[p1]! > ranks[p2]! {
+            parents[p2] = p1
+        } else if ranks[p1]! < ranks[p2]! {
+            parents[p1] = p2
+        } else {
+            parents[p1] = p2
+            ranks[p2, default: 0] += 1
+        }
+        return true
+    }
+}
+
+class Solution {
+    func findRedundantConnection(_ edges: [[Int]]) -> [Int] {
+        let unionFind = UnionFind(n: edges.count)
+        for edge in edges {
+            if !unionFind.union(n1: edge[0], n2: edge[1]) {
+                return [edge[0], edge[1]]
+            }
+        }
+        return []
+    }
+}