[Swift]LeetCode721. 账户合并 | Accounts Merge

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Given a list accounts, each element accounts[i] is a list of strings, where the first element accounts[i][0] is a name, and the rest of the elements are emails representing emails of the account.

Now, we would like to merge these accounts. Two accounts definitely belong to the same person if there is some email that is common to both accounts. Note that even if two accounts have the same name, they may belong to different people as people could have the same name. A person can have any number of accounts initially, but all of their accounts definitely have the same name.

After merging the accounts, return the accounts in the following format: the first element of each account is the name, and the rest of the elements are emails in sorted order. The accounts themselves can be returned in any order.

Example 1:

Input: 
accounts = [["John", "johnsmith@mail.com", "john00@mail.com"], ["John", "johnnybravo@mail.com"], ["John", "johnsmith@mail.com", "john_newyork@mail.com"], ["Mary", "mary@mail.com"]]
Output: [["John", 'john00@mail.com', 'john_newyork@mail.com', 'johnsmith@mail.com'],  ["John", "johnnybravo@mail.com"], ["Mary", "mary@mail.com"]]
Explanation: 
The first and third John's are the same person as they have the common email "johnsmith@mail.com".
The second John and Mary are different people as none of their email addresses are used by other accounts.
We could return these lists in any order, for example the answer [['Mary', 'mary@mail.com'], ['John', 'johnnybravo@mail.com'], 
['John', 'john00@mail.com', 'john_newyork@mail.com', 'johnsmith@mail.com']] would still be accepted.

Note:

• The length of accounts will be in the range [1, 1000].
• The length of accounts[i] will be in the range [1, 10].
• The length of accounts[i][j] will be in the range [1, 30].

---

给定一个列表 accounts，每个元素 accounts[i] 是一个字符串列表，其中第一个元素 accounts[i][0] 是 名称 (name)，其余元素是 emails 表示该帐户的邮箱地址。

现在，我们想合并这些帐户。如果两个帐户都有一些共同的邮件地址，则两个帐户必定属于同一个人。请注意，即使两个帐户具有相同的名称，它们也可能属于不同的人，因为人们可能具有相同的名称。一个人最初可以拥有任意数量的帐户，但其所有帐户都具有相同的名称。

合并帐户后，按以下格式返回帐户：每个帐户的第一个元素是名称，其余元素是按顺序排列的邮箱地址。accounts 本身可以以任意顺序返回。

例子 1:

Input: 
accounts = [["John", "johnsmith@mail.com", "john00@mail.com"], ["John", "johnnybravo@mail.com"], ["John", "johnsmith@mail.com", "john_newyork@mail.com"], ["Mary", "mary@mail.com"]]
Output: [["John", 'john00@mail.com', 'john_newyork@mail.com', 'johnsmith@mail.com'],  ["John", "johnnybravo@mail.com"], ["Mary", "mary@mail.com"]]
Explanation: 
  第一个和第三个 John 是同一个人，因为他们有共同的电子邮件 "johnsmith@mail.com"。 
  第二个 John 和 Mary 是不同的人，因为他们的电子邮件地址没有被其他帐户使用。
  我们可以以任何顺序返回这些列表，例如答案[['Mary'，'mary@mail.com']，['John'，'johnnybravo@mail.com']，
  ['John'，'john00@mail.com'，'john_newyork@mail.com'，'johnsmith@mail.com']]仍然会被接受。

注意：

• accounts的长度将在[1，1000]的范围内。
• accounts[i]的长度将在[1，10]的范围内。
• accounts[i][j]的长度将在[1，30]的范围内。

---

552ms

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        var dsu = DSU()
        for account in accounts {
            var emails = Array(account[1...])
            var name = account[0]
            dsu.addEdge(emails, name)
        }
        return dsu.unions()
    }
}

struct DSU {
    var mapping: [String: Int] = [:]
    var arr: [Int]
    var size: [Int]
    var comps: Int
    var names: [Int: String] = [:]
    
    mutating func unions() -> [[String]] {
        var res = [String: [String]]()
        for (email, index) in mapping {
            let parent = find(index)
            res["\(names[parent]!):\(parent)", default: []].append(email)
        }
        return res.map { arg0 in
            var (key, val) = arg0
            key = String(key.split(separator: ":")[0])
            return [key] + val.sorted()
        }
    }
    
    init() {
        arr = []
        size = []
        comps = 0
    }
    
    init(n: Int) {
        comps = n
        arr = Array(repeating: 0, count: n)
        size = Array(repeating: 1, count: n)
        for i in 0..<n {
            arr[i] = i
        }
    }
    
    mutating func addEdge(_ edge: [String], _ name: String) {
        if mapping[edge[0]] == nil {
            arr.append(arr.count)
            size.append(1)
            mapping[edge[0]] = arr.count - 1
            names[arr.count - 1] = name
        }
        for i in 1..<edge.count {
            if mapping[edge[i]] == nil {
                arr.append(arr.count)
                size.append(1)
                mapping[edge[i]] = arr.count - 1
            }
            union(mapping[edge[0]]!, mapping[edge[i]]!)
        }
    }
    
    mutating func find(_ a: String, _ b: String) -> Bool {
        guard let indA = mapping[a], let indB = mapping[b] else { return false }
        return find(indA, indB)
    }
    
    mutating func find(_ a: Int) -> Int {
        return root(a)
    }
    
    mutating func union(_ a: Int, _ b: Int) {
        let rootA = root(a)
        let rootB = root(b)
        if rootA == rootB {
            return
        }
        if size[a] >= size[b] {
            arr[rootB] = rootA
            size[a] += size[b]
        } else {
            arr[rootA] = rootB
            size[b] += size[a]
        }
        comps -= 1
    }
    
    mutating func find(_ a: Int, _ b: Int) -> Bool {
        return root(a) == root(b)
    }
    
    private mutating func root(_ index: Int) -> Int {
        var index = index
        while arr[index] != index {
            arr[index] = arr[arr[index]]
            index = arr[index]
        }
        return index
    }
}

---

704ms

class Solution {
    class UnionManager {
        var idMap = [String: Int]()
        var setMap = [Int]()
        
        func add(element: String) -> Int {
            if idMap[element] == nil{
                let idForElement = setMap.count
                idMap[element] = idForElement
                setMap.append(idForElement)
            }
            return idMap[element] ?? 0
        }
        
        func findSet(id: Int) -> Int {
            if setMap[id] != id {
                setMap[id] = findSet(id: setMap[id])
            }
            return setMap[id]
        }
        
        func union(setOf string1: String, with string2: String) {
            let id1 = add(element: string1)
            let id2 = add(element: string2)
            setMap[findSet(id: id1)] = findSet(id: id2)
        }
    }
    
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        let unionManager = UnionManager()
        var emailToName = [String: String]()
        let nonEmptyAccounts = accounts.filter{ $0.count > 1 }
        for account in nonEmptyAccounts {
            let name = account[0]
            for email in account[1..<account.count] {
                emailToName[email] = name
                unionManager.union(setOf: email, with: account[1])
            }
        }
        var results: [Int: [String]] = [:]
        for (email, id) in unionManager.idMap {
            let setId = unionManager.findSet(id: id)
            results[setId, default: []].append(email)
        }
        return results.values.map { $0.sorted() }
        .map { emailList in
              if let name = emailToName[emailList[0]] {
                  return [name] + emailList
              } else {
                  return emailList
              }
         }
    }
}

---

732ms

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        guard accounts.count > 0 else {
            return []
        }
        let graph = Graph<String>(.undirected)
        var emailToNameDictionary: [String: String] = [:]
        for account in accounts {
            let name = account[0]
            let source = graph.createVertex(account[1])
            for i in 1..<account.count {
                let email = account[i]
                emailToNameDictionary[email] = name
                if i > 1 {
                    let destination = graph.createVertex(account[i])
                    graph.addUndirectedEdge(between: source, and: destination)
                }
            }
        }
        var mergedAccounts: [[String]] = []
        var discovered: Set<Vertex<String>> = []
        for vertex in graph.vertice {
            if !discovered.contains(vertex) {
                var emails: [String] = []
                depthFirstSearch(graph, vertex, &discovered, &emails)
                let result = [emailToNameDictionary[vertex.val]!] + emails.sorted()
                mergedAccounts.append(result)
            }
        }
        
        return mergedAccounts
    }
}

func depthFirstSearch<T: Hashable>(_ graph: Graph<T>, 
                                   _ source: Vertex<T>, 
                                   _ discovered: inout Set<Vertex<T>>, 
                                   _ emails: inout [T]
                                  ) {
    discovered.insert(source)
    emails.append(source.val)
    for edge in graph.edges(of: source) {
        let destination = edge.destination
        if !discovered.contains(destination) {
            depthFirstSearch(graph, destination, &discovered, &emails)
        }
    }
}


enum GraphType {
    case directed 
    case undirected 
}

struct Vertex<T: Hashable>: Hashable {
    public var val: T 
    public init(_ val: T) {
        self.val = val
    }
    
    public var hashValue : Int {
        return val.hashValue
    }
    
    public static func ==(lhs: Vertex<T>, rhs: Vertex<T>) -> Bool {
        return lhs.val == rhs.val
    }
}

struct Edge<T: Hashable> {
    public let source: Vertex<T>
    public let destination: Vertex<T>
    public let weight: Double? 
    public init(source: Vertex<T>, destination: Vertex<T>, weight: Double? = nil ) {
        self.source = source 
        self.destination = destination 
        self.weight = weight 
    }
}


class Graph<T: Hashable> {
    public var vertice: [Vertex<T>] = []
    private var adjacencyList: [Vertex<T>: [Edge<T>]] = [:]
    public var type: GraphType 
    
    public init(_ type: GraphType) {
        self.type = type
    }
    
    public func createVertex(_ val: T) -> Vertex<T> {
        let source = Vertex(val)
        if adjacencyList[source] == nil {
            adjacencyList[source] = []
            vertice.append(source)
        }
        return source 
    }
    
    public func addDirectedEdge(from source: Vertex<T>, 
                                to destination: Vertex<T>, 
                                weight: Double? = nil 
                               ) {
        let edge = Edge(source: source, destination: destination, weight: weight)
        adjacencyList[source]?.append(edge)
    }
    
    public func addUndirectedEdge(between source: Vertex<T>,
                                  and destination: Vertex<T>, 
                                  weight: Double? = nil 
                                 ) {
        addDirectedEdge(from: source, to: destination, weight: weight)
        addDirectedEdge(from: destination, to: source, weight: weight)
    }
    
    public func edges(of source: Vertex<T>) -> [Edge<T>] {
        return adjacencyList[source] ?? []
    }
    
    public func weight(from source: Vertex<T>, 
                       to destination: Vertex<T>
                      ) -> Double? {
        return adjacencyList[source]?.first{ $0.destination == destination }?.weight 
    }
}

---

852ms

class Solution {
// father[儿子] = 老大哥
var father = [Int: Int]()

func accountsMerge(_ accounts: [[String]]) -> [[String]] {
    
    // 1 union
    let emailToID = getEmailToID(accounts)
    for email in emailToID.keys {
        let ids = emailToID[email]!
        for i in ids {
            union(i, ids[0])
        }
    }
    
    //2 merge
    let idToEmailSet = getIdToEmailSet(accounts)
    var mergedAccounts = [[String]]()
    
    for id in idToEmailSet.keys {
        var sortedEmails = idToEmailSet[id]!.sorted()
        sortedEmails.insert(accounts[id][0], at: 0)
        mergedAccounts.append(sortedEmails)
    }
    
    return mergedAccounts
}

//find -> 找老大哥
func find(_ id: Int) -> Int {
    var id = id
    
    var path = [Int]()
    while let nextID = father[id] {
        path.append(id)
        id = nextID
        
    }
    
    for i in path {
        father[i] = id
    }
    
    return id
}

// union
func union(_ a: Int, _ b: Int) {
    let rootA = find(a)
    let rootB = find(b)
    if rootA != rootB {
        father[rootA] = rootB
    }
}


// 这个只是data处理
func getEmailToID(_ accounts: [[String]]) -> [String: [Int]] {
    var emailToID = [String: [Int]]()
    
    for (userID, acnt) in accounts.enumerated() {
        for i in 1..<acnt.count {
            let curEmail = acnt[i]
            var ids = emailToID[curEmail, default: [Int]()]
            ids.append(userID)
            emailToID[curEmail] = ids
        }
    }
    
    return emailToID
}

func getIdToEmailSet(_ accounts: [[String]]) -> [Int: Set<String>] {
    var idToEmailSet = [Int: Set<String>]()
    for id in 0..<accounts.count {
        let root_id = find(id)
        var emailSet = idToEmailSet[root_id, default: Set<String>()]
        
        let account = accounts[id]
        for i in 1..<account.count {
            emailSet.insert(account[i])
        }
        idToEmailSet[root_id] = emailSet
    }
    
    return idToEmailSet
  }
}

---

864ms

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        guard accounts.count > 0 else {
            return []
        }
        
        var emailToName: [String: String] = [:]
        var unionFind = UnionFind<String>()
        for account in accounts {
            let name = account[0]
            let firstEmail = account[1]
            unionFind.addSet(firstEmail)
            for i in 1..<account.count {
                let email = account[i]
                emailToName[email] = name
                
                if i > 1 {
                    let email = account[i]
                    unionFind.addSet(email)
                    unionFind.union(firstEmail, email)
                }
            }
        }
        
        var mergedAccount: [[String]] = []
        var storage: [Int: [String]] = [:]
        for element in unionFind.index.keys {
            let parentIndex = unionFind.find(element)!
            if storage[parentIndex] == nil {
                storage[parentIndex] = [element]
            } else {
                storage[parentIndex]!.append(element)
            }
        }
        
        for emails in storage.values {
            let name = emailToName[emails.first!]!
            let result = [name] + emails.sorted()
            mergedAccount.append(result)
        }
        
        
        return mergedAccount
    }
}


struct UnionFind<T: Hashable> {
    public var index: [T: Int] = [:]
    private var parent: [Int] = []
    private var size: [Int] = []
    
    public mutating func addSet(_ element: T) {
        if index[element] == nil {
            index[element] = parent.count 
            parent.append(parent.count)
            size.append(1)
        }
    }
    
    public mutating func find(_ element: T) -> Int? {
        guard let index = index[element] else {
            return nil 
        }
        
        return setByIndex(index)
    }
    
    private mutating func setByIndex(_ index: Int) -> Int {
        if parent[index] == index {
            return index 
        } else {
            parent[index] = setByIndex(parent[index])
            return parent[index]
        }
    }
    
    public mutating func union(_ element1: T, _ element2: T) {
        guard let set1 = find(element1), let set2 = find(element2) else {
            return 
        }
        
        if set1 != set2 {
            if set1 > set2 {
                parent[set2] = set1
                size[set1] += size[set2]
            } else {
                parent[set1] = set2
                size[set2] += size[set1]
            }
        }
    }
}

---

Runtime: 1180 ms

Memory Usage: 21 MB

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        var res:[[String]] = [[String]]()
        var root:[String:String] = [String:String]()
        var owner:[String:String] = [String:String]()
        var m:[String:Set<String>] = [String:Set<String>]()
        for account in accounts
        {
            for i in 1..<account.count
            {
                root[account[i]] = account[i]
                owner[account[i]] = account[0]
            }
        }
        for account in accounts
        {
            var p:String = find(account[1], &root)
            for i in 2..<account.count
            {
                root[find(account[i], &root)] = p                
            }
        }
        for account in accounts
        {
            for i in 1..<account.count
            {
                let str:String = find(account[i], &root)
                m[str,default:Set<String>()].insert(account[i])
            }
        }
        for (key,val) in m
        {
            var v:[String] = val.sorted()
            v.insert(owner[key,default:String()],at:0)
            res.append(v)
        }
        return res
    }
    
    func find(_ s:String,_ root:inout [String:String]) -> String
    {
        return root[s] == s ? s : find(root[s,default:String()], &root)
    }
}

---

2348ms

class Solution {    
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        var emailIdDict: [String:Int] = [:]
        var idNameDict: [Int:String] = [:]
        var idEmailsDict: [Int:[String]] = [:]
        
        var curId = 0
        
        for account in accounts {
            // Get name
            let name = account[0]
            
            // Make sure emails exist
            guard account.count > 1 else {
                idNameDict[curId] = name
                curId += 1
                continue
            }
            
            // Get emails
            let emails = Array(account[1..<account.count])
            
            // Get matching ids for emails
            var idMatches: [Int] = []
            emails.forEach({
                guard let id = emailIdDict[$0] else { return }
                idMatches.append(id)
            })
            idMatches = Array(Set(idMatches)).sorted()
            
            // Get all combined emails
            var allEmails: [String] = emails
            idMatches.forEach({
                allEmails += idEmailsDict[$0] ?? []
                idNameDict.removeValue(forKey: $0)
                idEmailsDict.removeValue(forKey: $0)
            })
            
            // Write data to dicts
            allEmails.forEach({ emailIdDict[$0] = curId })
            idNameDict[curId] = name
            idEmailsDict[curId] = allEmails
            
            // Incrememt ID
            curId += 1
        }
        
        return Array(idNameDict.keys).compactMap({
            guard let name = idNameDict[$0] else { return nil }
            let emails = Array(Set((idEmailsDict[$0] ?? []))).sorted()
            return [name] + emails
        })
    }
}

---

2708ms

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        var mAccountsMap = [String: [Set<String>]]()
        for sa in accounts {
            let sets = mAccountsMap[sa[0]] ?? [Set<String>]()
            let mergeset = Set(Array(sa[1..<sa.count]))
            let (mergesets, _) = mergeSets(mergeset, sets)
            // print(mergesets)
            mAccountsMap[sa[0]] = mergesets
        }

        var result = [[String]]()
        for (act, mailsSetArr) in mAccountsMap {
            for set in mailsSetArr {            
                var line = [String]()
                line.append(act)
                line.append(contentsOf: Array(set.sorted()))
                result.append(line)
            }
        }
        return result
    }

    func mergeSets(_ mergeSet: Set<String>, _ sets: [Set<String>]) -> ([Set<String>], Bool) {
        var ans = sets
        var merged = false
        var valildUionSet = Set<String>()
        for i in 0..<sets.count {
            let set = sets[i]
            if !set.intersection(mergeSet).isEmpty {
                var uniSets = set
                uniSets.formUnion(mergeSet)
                merged = true
                ans.remove(at: i)
                valildUionSet = uniSets
                break
            }
        }
        if !merged {
            ans.append(mergeSet)
        }
        return merged ? mergeSets(valildUionSet, ans) : (ans, false)
    }
}

---

2852ms

class Solution {
    func accountsMerge(_ accounts: [[String]]) -> [[String]] {
        var name = ""
        var emailSets = [Set<String>]()
        var results = [[String]]()
        var sortedAccounts = accounts.sorted { return $0[0] < $1[0] }
        for account in sortedAccounts {
            if !name.isEmpty && account[0] != name {
                for setFound in emailSets {
                    results.append([name] + Array(setFound).sorted())
                }
                emailSets = []
            }
            name = account[0]
            var currentEmailSet = Set(account[1..<account.count])
            var newSets = [Set<String>]()
            for (i, existingSet) in emailSets.enumerated() {
                if !currentEmailSet.intersection(existingSet).isEmpty {
                    currentEmailSet = currentEmailSet.union(existingSet)
                } else {
                    newSets.append(existingSet)
                }
            }
            newSets.append(currentEmailSet)
            emailSets = newSets
        }
        for setFound in emailSets {
            results.append([name] + Array(setFound).sorted())
        }
        return results
    }
}