Create 0721-accounts-merge.swift

Author: drxlx

swift/0721-accounts-merge.swift

@@ -0,0 +1,68 @@
+/**
+ * Question Link: https://leetcode.com/problems/accounts-merge/
+ */
+
+ class UnionFind {
+    var parents = [Int: Int]()
+    var ranks = [Int: Int]()
+
+    init(n: Int) {
+        for i in 0..<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 accountsMerge(_ accounts: [[String]]) -> [[String]] {
+        let unionFind = UnionFind(n: accounts.count)
+        var emailToAcc = [String: Int]()
+        for (i, a) in accounts.enumerated() {
+            for j in 1..<a.count {
+                if let index = emailToAcc[a[j]] {
+                    unionFind.union(n1: i, n2: index)
+                } else {
+                    emailToAcc[a[j]] = i
+                }
+            }
+        }
+        var emailGroup = [Int: [String]]()
+        for (e, i) in emailToAcc {
+            let leader = unionFind.find(n: i)
+            emailGroup[leader, default: []].append(e)
+        }
+        var res = [[String]]()
+        for (i, emails) in emailGroup {
+            let name = accounts[i][0]
+            res.append([name] + emails.sorted())
+        }
+        return res
+    }
+}