#233
Number of Digit One
hard · verified · 37.8% accepted · 1,820 likes · top 16%
math · dynamic programming · recursion
Description
Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.
Example 1:
Input: n = 13
Output: 6
Example 2:
Input: n = 0
Output: 0
Solution