[Swift]LeetCode179. 最大数 | Largest Number

★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★
➤微信公众号：山青咏芝（shanqingyongzhi）
➤博客园地址：山青咏芝（https://www.cnblogs.com/strengthen/）
➤GitHub地址：https://github.com/strengthen/LeetCode
➤原文地址：https://www.cnblogs.com/strengthen/p/10151582.html 
➤如果链接不是山青咏芝的博客园地址，则可能是爬取作者的文章。
➤原文已修改更新！强烈建议点击原文地址阅读！支持作者！支持原创！
★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★★

热烈欢迎，请直接点击！！！

进入博主App Store主页，下载使用各个作品！！！

注：博主将坚持每月上线一个新app！！！

Given a list of non negative integers, arrange them such that they form the largest number.

Example 1:

Input: [10,2]
Output: "210"

Example 2:

Input: [3,30,34,5,9]
Output: "9534330"

Note: The result may be very large, so you need to return a string instead of an integer.

---

给定一组非负整数，重新排列它们的顺序使之组成一个最大的整数。

示例 1:

输入: [10,2]
输出: 210

示例 2:

输入: [3,30,34,5,9]
输出: 9534330

说明: 输出结果可能非常大，所以你需要返回一个字符串而不是整数。

---

20ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        var nums = nums
        var res:String = String()
        nums.sort(by:{(num1:Int,num2:Int) -> Bool in
            return String(num1) + String(num2) > String(num2) + String(num1)
        })
        
        for i in 0..<nums.count
        {
            res += String(nums[i])
        }
        return res[0] == "0" ? "0" : res
    }
}

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)]}
    }
}

---

20ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        var arr = nums.compactMap{ return String($0) }
        arr.sort{ return $0 + $1 > $1 + $0 }
        while arr.count > 1 && arr[0] == "0" {
            arr.removeFirst()
        }
        return arr.joined(separator: "")
    }
}

---

24ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
let s = nums.map({ (i) -> String in
        "\(i)"
    }).sorted { (i, j) -> Bool in
         (i + j) > (j + i)
        }
    if s.count == 0 || s[0] == "0" {
        return "0"
    }
    return s.reduce("") { (res, t) -> String in
        res + t
    }
    }
}

---

28ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        let strs = nums.map{"\($0)"}.sorted { (str1, str2) -> Bool in
            return str1 + str2 > str2 + str1
        }
        let s = strs.joined()
        if(s.first != "0"){ return s }
        return "0"
    }
}

---

28ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        var numsPermuation : [String] = []
        
        for i in 0..<nums.count {
            numsPermuation.append(String(nums[i]))
        }
        
        var result = numsPermuation.map{$0}.sorted(by: {$0 + $1 > $1 + $0}).joined()
        
        return result.first == "0" ? "0" : result

    }
}

---

32ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        var nums = nums
        nums.sort{ String($0) + String($1) > String($1) + String($0) }
        var result = ""
        var flag = false
        for i in nums{
            if i != 0 {
                flag = true
            }
            if flag {
                result = result + String(i)   
            }
        }
        if result.count == 0 {
            result = "0"
        }
        return result
    }
}

---

 32ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {

        var res =  nums.map{String($0)}.sorted{ return $0 + $1 > $1 + $0 }.joined()
        return res.first == "0" ? "0" : res
    }
}

---

48ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        guard nums.count > 0 else {
            return ""
        }
        
        var n = nums.map({ String($0) })
        
        n.sort { (n1, n2) -> Bool in
            let s1 = Int(n1 + n2)!
            let s2 = Int(n2 + n1)!
            return s1 > s2
        }
        
        
        let result = n.joined()
        
        
        return n[0] == "0" ? "0" : result
    }
}

---

48ms

class Solution {
    func largestNumber(_ nums: [Int]) -> String {
        let array = nums.sorted { return "\($0)\($1)" > "\($1)\($0)" }
        var result = ""
        if let firstNum = array.first, firstNum == 0 {
            return "0"
        }
        for num in array {
            result += "\(num)"
        }
        return result
    }
}