Number of Steps to Reduce a Number to Zero

Simulation / Bit Counting

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Asked in interviews at

1 in the last 6 months

Meta
Hudson River Trading
Google

Microsoft

Amazon

Bloomberg

Community-reported company tags from leetcode-company-wise-problems (updated 2026-10-08). Bar shows how often each company asks it.

Problem

Problem Statement

Given an integer num, return the number of steps to reduce it to zero.

In one step, if the current number is even, you divide it by 2, otherwise you subtract 1 from it.

Input / Output

Input:  num = 14
Output: 6
Explanation: 14 → 7 → 6 → 3 → 2 → 1 → 0

Input:  num = 8
Output: 4
Explanation: 8 → 4 → 2 → 1 → 0

Input:  num = 123
Output: 12

Constraints

0 ≤ num ≤ 10^6

Understanding the Problem

Even → num /= 2 (in binary: shift right, drops a 0)
Odd → num -= 1 (in binary: clears the lowest 1)

Edge Cases

num = 0 → 0 steps
num = 1 → 1 step

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