[Swift]LeetCode811. 子域名访问计数 | Subdomain Visit Count

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A website domain like "discuss.leetcode.com" consists of various subdomains. At the top level, we have "com", at the next level, we have "leetcode.com", and at the lowest level, "discuss.leetcode.com". When we visit a domain like "discuss.leetcode.com", we will also visit the parent domains "leetcode.com" and "com" implicitly.

Now, call a "count-paired domain" to be a count (representing the number of visits this domain received), followed by a space, followed by the address. An example of a count-paired domain might be "9001 discuss.leetcode.com".

We are given a list cpdomains of count-paired domains. We would like a list of count-paired domains, (in the same format as the input, and in any order), that explicitly counts the number of visits to each subdomain.

Example 1:
Input: 
["9001 discuss.leetcode.com"]
Output: 
["9001 discuss.leetcode.com", "9001 leetcode.com", "9001 com"]
Explanation: 
We only have one website domain: "discuss.leetcode.com". As discussed above, the subdomain "leetcode.com" and "com" will also be visited. So they will all be visited 9001 times.

Example 2:
Input: 
["900 google.mail.com", "50 yahoo.com", "1 intel.mail.com", "5 wiki.org"]
Output: 
["901 mail.com","50 yahoo.com","900 google.mail.com","5 wiki.org","5 org","1 intel.mail.com","951 com"]
Explanation: 
We will visit "google.mail.com" 900 times, "yahoo.com" 50 times, "intel.mail.com" once and "wiki.org" 5 times. For the subdomains, we will visit "mail.com" 900 + 1 = 901 times, "com" 900 + 50 + 1 = 951 times, and "org" 5 times.

Notes:

• The length of cpdomains will not exceed 100. 
• The length of each domain name will not exceed 100.
• Each address will have either 1 or 2 "." characters.
• The input count in any count-paired domain will not exceed 10000.
• The answer output can be returned in any order.

---

一个网站域名，如"discuss.leetcode.com"，包含了多个子域名。作为顶级域名，常用的有"com"，下一级则有"leetcode.com"，最低的一级为"discuss.leetcode.com"。当我们访问域名"discuss.leetcode.com"时，也同时访问了其父域名"leetcode.com"以及顶级域名 "com"。

给定一个带访问次数和域名的组合，要求分别计算每个域名被访问的次数。其格式为访问次数+空格+地址，例如："9001 discuss.leetcode.com"。

接下来会给出一组访问次数和域名组合的列表cpdomains 。要求解析出所有域名的访问次数，输出格式和输入格式相同，不限定先后顺序。

示例 1:
输入: 
["9001 discuss.leetcode.com"]
输出: 
["9001 discuss.leetcode.com", "9001 leetcode.com", "9001 com"]
说明: 
例子中仅包含一个网站域名："discuss.leetcode.com"。按照前文假设，子域名"leetcode.com"和"com"都会被访问，所以它们都被访问了9001次。

示例 2
输入: 
["900 google.mail.com", "50 yahoo.com", "1 intel.mail.com", "5 wiki.org"]
输出: 
["901 mail.com","50 yahoo.com","900 google.mail.com","5 wiki.org","5 org","1 intel.mail.com","951 com"]
说明: 
按照假设，会访问"google.mail.com" 900次，"yahoo.com" 50次，"intel.mail.com" 1次，"wiki.org" 5次。
而对于父域名，会访问"mail.com" 900+1 = 901次，"com" 900 + 50 + 1 = 951次，和 "org" 5 次。

注意事项：

•  cpdomains 的长度小于 100。
• 每个域名的长度小于100。
• 每个域名地址包含一个或两个"."符号。
• 输入中任意一个域名的访问次数都小于10000。

---

Runtime: 92 ms

Memory Usage: 19.8 MB

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var res:[String] = [String]()
        var subdomainCnt:[String:Int] = [String:Int]()
        for cpdomain in cpdomains
        {
            var spaceIdx = cpdomain.index(of: " ")!
            var cnt:Int = Int(String(cpdomain[cpdomain.startIndex..<spaceIdx])) ?? 0
            var rem:String = String(cpdomain[spaceIdx..<cpdomain.endIndex])
            rem.remove(at:rem.startIndex)
            for i in 0..<rem.count
            {
                if rem[i] == "."
                {
                    subdomainCnt[rem.subString(i + 1),default:0] += cnt
                }
            }
            subdomainCnt[rem,default:0] += cnt            
        }
        for (key,val) in subdomainCnt
        {
            res.append(String(val) + " " + key)
        }
        return res
    }
}

//String扩展
extension String {        
    //subscript函数可以检索数组中的值
    //直接按照索引方式截取指定索引的字符
    subscript (_ i: Int) -> Character {
        //读取字符
        get {return self[index(startIndex, offsetBy: i)]}
    }
    
    // 截取字符串：从index到结束处
    // - Parameter index: 开始索引
    // - Returns: 子字符串
    func subString(_ index: Int) -> String {
        let theIndex = self.index(self.endIndex, offsetBy: index - self.count)
        return String(self[theIndex..<endIndex])
    }
}

---

92ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var domainDict = Dictionary<String, Int>()
        var result = [String]()
        for cpdomain in cpdomains {
            let domainPair = cpdomain.split(separator: " ")
            let count = Int(domainPair[0])!
            var domain = String(domainPair[1])
            domainDict[domain] = (domainDict[domain] ?? 0) + count
            while let index = domain.firstIndex(of: ".") {
                domain.removeSubrange(domain.startIndex...index)
                domainDict[domain] = (domainDict[domain] ?? 0) + count
            }
        }
        for (d, c) in domainDict {
            result.append("\(c) \(d)")
        }
        return result
    }
}

---

96ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var result = [String: Int]()
        cpdomains.forEach { (cpdomain) in
            let parts = cpdomain.split(separator: " ")
            let times = Int(parts[0]) ?? 0
            var domain = String(parts[1])
            
            result[domain] = (result[domain] ?? 0) + times
            
            while let dotIndex = domain.index(of: ".") {
                domain.removeSubrange(domain.startIndex...dotIndex)
                result[domain] = (result[domain] ?? 0) + times
            }
        }
        return result.reduce(into: []) { (a, pair) in
            a.append("\(pair.value) \(pair.key)")
        }
    }
}

---

98ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var res = [String: Int]()

        for domain in cpdomains {
            let splits = domain.split(separator: " ").map { String($0) }
            let count = Int(splits[0])!
            let domain = splits[1]
            let frags = domain.split(separator: ".").map { String($0) }
            var curr = [String]()
            for i in Array(0..<frags.count).reversed() {
                curr.append(frags[i])
                let subdomain = curr.reversed().joined(separator: ".")
                res[subdomain] = (res[subdomain] ?? 0) + count
            }
         }

        return res.map { "\($0.value) \($0.key)" }
    }
}

---

100ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var ans = [String : Int]();
        for domain in cpdomains {
            let t = domain.split(separator: " ")
            let count = Int(t[0])!
            let domains = t[1].split(separator: ".")
            var computedDomain = ""
            for s in domains.reversed() {
                if computedDomain == "" {
                    computedDomain = String(s)
                } else {
                    computedDomain = s + "." + computedDomain
                }
                if let c = ans[computedDomain] {
                  ans[computedDomain] = count + c
                } else {
                  ans[computedDomain] = count
                }
            }
        }
        
        let result = ans.map { (k, v)  in
            "\(v) \(k)"
        }              
        return result
    }
}

---

104ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var dict = [String: Int]()
        for domain in cpdomains {
            let items = domain.split(separator: " ")
            let cpdo = items[1].split(separator: ".")
            var key = ""
            for i in (0..<cpdo.count).reversed() {
                if i != cpdo.count - 1 {
                    key = "." + key
                } 
                key = cpdo[i] + key
                dict[key] = dict[key] ?? 0
                dict[key]! += Int(items[0])!
            }
        }
        var result = [String]()
        for (key, value) in dict {
            result.append(String(value) + " " + key)
        }
        return result
    }
}

---

108ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var dict: [String: Int] = [:]
        cpdomains.forEach({ countAndDomain in
            let count = Int(countAndDomain.split(separator: " ")[0]) ?? 0
            var domain = String(countAndDomain.split(separator: " ")[1])
            dict[domain] = (dict[domain] ?? 0) + count
            while let dotIndex = domain.firstIndex(of: ".") {
                domain.removeSubrange(domain.startIndex...dotIndex)
                dict[domain] = (dict[domain] ?? 0) + count
            }
        })
        return dict.reduce([String](), {a, pair in
            var a = a
            a.append("\(pair.value) \(pair.key)")
            return a
        })
    }
}

---

116ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var result:[String: Int] = [String: Int]()
        for domain in cpdomains {
            let split = domain.split(separator: " ")
            if let countString = split.first, let count = Int(countString), let domains = split.last {
                let domainComponents = Array(domains.split(separator: ".").reversed())
                for idx in 0..<domainComponents.count {
                    let curr = Array(domainComponents[0...idx].reversed())
                    let currDomain = String(curr.joined(separator: ".")).lowercased()
                    result[currDomain] = (result[currDomain] ?? 0) + count
                }
            }
        }
        
        var answer: [String] = [String]()
        for (key, val) in result {
            answer.append("\(val) \(key)")
        }
        return answer
    }
}

---

144ms

class Solution {
  func subdomainVisits(_ cpdomains: [String]) -> [String] {
    var results: [String:Int] = [:]
    cpdomains.forEach { domain in
      let splited = domain.components(separatedBy: " ")
      if splited.count > 1 {
        let counter = splited[0]
        let splitedDomain = splited[1]
        
        let dots = splitedDomain.components(separatedBy: ".")
        for i in 0..<(dots.count) {
          var d = dots[i]
          for j in (i+1)..<dots.count {
            d += "." + dots[j]
          }
          results[d] = (Int(counter) ?? 0) + (results[d] ?? 0)
        }
      }
    }
    return results.map { String($0.1) + " " + $0.0 }
  }
}

---

156ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
        var dict = [String: Int]()
        for e in cpdomains {
            let c = e.components(separatedBy: " ")
            let count = Int(c[0])!
            let domain = c[1]
            let subdomains = domain.components(separatedBy: ".")
            for i in subdomains.indices {
                let sub = subdomains[i...].joined(separator: ".")
                dict[sub, default: 0] += count 
            }
        }
        return dict.map { "\($0.value) \($0.key)"}
    }
}

---

172ms

class Solution {
    func subdomainVisits(_ cpdomains: [String]) -> [String] {
      var res = [String]()
      var dict = [String: Int]()  
       for cpdomain in cpdomains {
           let visit = retrieveCount(cpdomain)
           let count = Int(visit) ?? 0
           let domain = retrieveDomain(cpdomain)
           var subdomains = domain.components(separatedBy: ".")
           while (subdomains.count > 0) {
               let str = subdomains.joined(separator: ".")
               if var visited = dict[str] {
                   visited += count
                   dict.updateValue(visited, forKey: str)
               } else {
                   dict.updateValue(count, forKey: str)
               }
               subdomains.removeFirst()
           }
       }
      
       for subdomain in dict.keys {
           let visits = dict[subdomain] ?? 0
           let cpdomain = String(visits) + " " + subdomain
           res.append(cpdomain)
       } 
      return res
    }
    
    func retrieveDomain(_ cpdomain: String) -> String {
        let parts = cpdomain.components(separatedBy: " ")
        return parts.last ?? ""
    }
    
    func retrieveCount(_ cpdomain: String) -> String {
        let parts = cpdomain.components(separatedBy: " ")
        return parts.first ?? ""
    }
}