Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.
Example:
Input: 13 Output: 6 Explanation: Digit 1 occurred in the following numbers: 1, 10, 11, 12, 13.
给定一个整数 n,计算所有小于等于 n 的非负整数中数字 1 出现的个数。
示例:
输入: 13 输出: 6 解释: 数字 1 出现在以下数字中: 1, 10, 11, 12, 13 。
8ms
1 class Solution { 2 func countDigitOne(_ n: Int) -> Int { 3 var n = n 4 var rest = 0 5 var base = 1 6 var count = 0 7 8 while n > 0 { 9 let digit = n % 10 10 n = n/10 11 count += n * base 12 switch digit { 13 case 0: () 14 case 1: count += rest + 1 15 default: count += base 16 } 17 rest = digit * base + rest 18 base *= 10 19 } 20 return count 21 } 22 }
8ms
1 class Solution { 2 func countDigitOne(_ n: Int) -> Int { 3 var num = n 4 var res = 0 5 var multiply = 1 6 var remainder = 0 7 while num > 0 { 8 let val = num % 10 9 10 if val <= 1 { 11 res += (num / 10) * multiply 12 if val == 1 { 13 res += remainder + 1 14 } 15 } 16 else { 17 res += (num / 10 + 1) * multiply 18 } 19 20 multiply *= 10 21 remainder = n % multiply 22 num /= 10 23 } 24 25 return res 26 } 27 }
12ms
1 class Solution { 2 func countDigitOne(_ n: Int) -> Int { 3 if n <= 0 { return 0 } 4 5 let digitCount = Int(log2(Double(n))/log2(10))+1 6 var count = 0 7 for i in 0..<digitCount { 8 let base = Int(pow(10, Double(i))) 9 let nextBase = base * 10 10 let currentDigit = n/base % 10 11 12 count += (n/nextBase) * base 13 14 if currentDigit == 0 { 15 count += 0 16 } else if currentDigit == 1 { 17 count += n % base + 1 18 } else { 19 count += base 20 } 21 } 22 return count 23 } 24 }
36ms
1 class Solution { 2 func countDigitOne(_ n: Int) -> Int { 3 if n <= 0 { 4 return 0 5 } 6 7 if n < 10 { 8 return 1 9 } 10 11 var m = n 12 var l = 0 13 var c = 1 14 while m != 0 { 15 l = m % 10 16 m /= 10 17 c *= 10 18 } 19 c /= 10 20 let k = l * c 21 22 if l == 1 { 23 return n - k + 1 + countDigitOne(n-k) + countDigitOne(c-1) 24 }else { 25 return countDigitOne(2 * c - 1) + (l - 2)*countDigitOne(c-1) + countDigitOne(n-k) 26 } 27 } 28 }
原文地址:https://www.cnblogs.com/strengthen/p/10204847.html
时间: 2024-10-07 16:24:21