0233. Number of Digit One

https://leetcode.com/problems/number-of-digit-one

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

Constraints:

• 0 <= n <= 109

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