[Swift]LeetCode1154. 一年中的第几天 | Ordinal Number Of Date

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Given a string date representing a (Gregorian) calendar date formatted as YYYY-MM-DD, return the ordinal number of that day in the same year.

(For example, Jan 1st has ordinal number 1, Jan 2nd has ordinal number 2, and so on.  For more information on the number of days in each month, see [Wiki: Gregorian Calendar]) 

Example 1:

Input: date = "2019-01-09"
Output: 9

Example 2:

Input: date = "2019-02-10"
Output: 41

Example 3:

Input: date = "2003-03-01"
Output: 60

Example 4:

Input: date = "2004-03-01"
Output: 61 

Constraints:

• date.length == 10
• date[4] == date[7] == '-', and all other date[i]'s are digits
• date represents a calendar date between Jan 1st, 1900 and Dec 31, 2019.

---

给你一个按 YYYY-MM-DD 格式表示日期的字符串 date，请你计算并返回该日期是当年的第几天。

通常情况下，我们认为 1 月 1 日是每年的第 1 天，1 月 2 日是每年的第 2 天，依此类推。每个月的天数与现行公元纪年法（格里高利历）一致。 

示例 1：

输入：date = "2019-01-09"
输出：9

示例 2：

输入：date = "2019-02-10"
输出：41

示例 3：

输入：date = "2003-03-01"
输出：60

示例 4：

输入：date = "2004-03-01"
输出：61 

提示：

• date.length == 10
• date[4] == date[7] == '-'，其他的 date[i] 都是数字。
• date 表示的范围从 1900 年 1 月 1 日至 2019 年 12 月 31 日。

---

Runtime: 4 ms

Memory Usage: 21.3 MB

class Solution {
    func dayOfYear(_ date: String) -> Int {
        let arrDate:[Int] = Array(date).map{$0.ascii}
        var Y:Int = 0
        var M:Int = 0
        var D:Int = 0
        Y+=(arrDate[0] - 48)*1000
        Y+=(arrDate[1] - 48)*100
        Y+=(arrDate[2] - 48)*10
        Y+=(arrDate[3] - 48)*1
        M+=(arrDate[5] - 48)*10
        M+=(arrDate[6] - 48)*1
        D+=(arrDate[8] - 48)*10
        D+=(arrDate[9] - 48)*1
        M -= 1
        var Ds:[Int] = [31,28,31,30,31,30,31,31,30,31,30,31]
        if Y%400 == 0
        {
            Ds[1] += 1
        }
        else if Y % 100 != 0 && Y % 4 == 0
        {
            Ds[1] += 1
        }
        for i in 0..<M
        {
            D+=Ds[i]
        }
        return D        
    }
}

//Character扩展 
extension Character  
{  
  //Character转ASCII整数值(定义小写为整数值)
   var ascii: Int {
       get {
           return Int(self.unicodeScalars.first?.value ?? 0)
       }       
    }
}

---

4ms

class Solution {
    func dayOfYear(_ date: String) -> Int {
        let days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
        let arr = Array(date)
        let y = Int(String(arr[0..<4]))!
        let m = Int(String(arr[5..<7]))!
        let d = Int(String(arr[8...]))!
        var res = 0
        for i in 0..<(m - 1) {
            res += days[i]
        }
        res += d
        if m > 2 && isLeap(y) {
            res += 1
        }
        return res
    }
    
    func isLeap(_ y: Int) -> Bool {
        if y % 4 != 0 { return false }
        else if y % 100 != 0 { return true }
        else if y % 400 != 0 { return false }
        return true
    }
}

---

8ms

class Solution {    
    func dayOfYear(_ date: String) -> Int {
        let dateParts = date.split(separator: "-")
        if dateParts.count != 3 {
            return -1
        }
        else {
            guard let year = Int(dateParts[0]) else {
                return -1
            }
            guard let month = Int(dateParts[1]) else {
                return -1
            }
            guard let day = Int(dateParts[2]) else {
                return -1
            }
            
            var isLeapYear = (year % 4 == 0)
            if (year % 100 == 0) {
                isLeapYear = (year % 400 == 0)
            }
            let monthToCumulativeNumDays = getMonthToCumulativeNumDays(isLeapYear)
            guard let cumulative = monthToCumulativeNumDays[month-1] else {
                return -1
            }
            return cumulative + day
        }
    }
    
    func getMonthToCumulativeNumDays(_ leapYear : Bool) -> [Int: Int]{
        var monthToCumulativeNumDays: [Int: Int] = [:]
        monthToCumulativeNumDays[0] = 0
        monthToCumulativeNumDays[1] = 31
        let febDays = leapYear ? 29 : 28
        monthToCumulativeNumDays[2] = febDays + monthToCumulativeNumDays[1]!
        monthToCumulativeNumDays[3] = 31 + monthToCumulativeNumDays[2]!
        monthToCumulativeNumDays[4] = 30 + monthToCumulativeNumDays[3]!
        monthToCumulativeNumDays[5] = 31 + monthToCumulativeNumDays[4]!
        monthToCumulativeNumDays[6] = 30 + monthToCumulativeNumDays[5]!
        monthToCumulativeNumDays[7] = 31 + monthToCumulativeNumDays[6]!
        monthToCumulativeNumDays[8] = 31 + monthToCumulativeNumDays[7]!
        monthToCumulativeNumDays[9] = 30 + monthToCumulativeNumDays[8]!
        monthToCumulativeNumDays[10] = 31 + monthToCumulativeNumDays[9]!
        monthToCumulativeNumDays[11] = 30 + monthToCumulativeNumDays[10]!
        monthToCumulativeNumDays[12] = 31 + monthToCumulativeNumDays[11]!
        return monthToCumulativeNumDays
    }
}

---

12ms

class Solution {
    struct Components {
        let day : Int
        let month : Int
        let year : Int
        
        init(withString s: String) {
            let comps = s.components(separatedBy:"-")
            year = Int(comps[0]) ?? 0
            month = Int(comps[1]) ?? 0
            day = Int(comps[2]) ?? 0
        }
        
        func isLeap() -> Bool {
            guard year % 4 == 0 else {
                return false
            }
            return year % 100 != 0 || year % 400 == 0
        }
        func daysInMonth(_ m: Int) -> Int {
            let dayCache = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
            if m == 2 && isLeap() {
                return 29
            }
            return dayCache[m-1]
        }
    }
    func dayOfYear(_ date: String) -> Int {
        let c = Components(withString: date)
        var result = 0
        var month = 1
        while month < c.month {
            result += c.daysInMonth(month)
            month += 1
        }
        return result + c.day
    }
}

---

36ms

class Solution {
    func dayOfYear(_ date: String) -> Int {
        let year = date[..<date.index(date.startIndex, offsetBy: 4)]
        let begin = "(year)-01-01"

        let format = DateFormatter()
        format.dateFormat = "yyyy-MM-dd"

        let startDate = format.date(from: begin)!
        let endDate = format.date(from: date)!

        let calendar = Calendar(identifier: .gregorian)
        let components = calendar.dateComponents([.day], from: startDate, to: endDate)
        return components.day!+1
    }
}

---

40ms

class Solution {
    func dayOfYear(_ date: String) -> Int {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd"
        let endDate = dateFormatter.date(from: date)!
        let year = date.components(separatedBy: "-").first!
        let startStr = year + "-01-01"
        let startDate = dateFormatter.date(from: startStr)!
        
        let days = Calendar.current.dateComponents([.day], from: startDate, to: endDate).day!
        return days + 1
    }
}