Number of Digit One · Coding Interview Practice

Number of Digit OneGiven an integer n, count the total number of times the digit 1 appears in all non-negative integers less than or equal to n.Constraints

0 <= n <= 10^9

Counting each number one by one is too slow

Examples

Input: n = 13 Output: 6

Input: n = 0 Output: 0

Practise this challengeAll coding challenges

LetsDiscuss

Loading your session…