How hard is LeetCode 1342. Number of Steps to Reduce a Number to Zero?

LeetCode 1342. Number of Steps to Reduce a Number to Zero is rated Easy on LeetCode.

What is the time complexity of LeetCode 1342. Number of Steps to Reduce a Number to Zero?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 1342. Number of Steps to Reduce a Number to Zero?

The Python solution on this page uses O(1) auxiliary space.

What topics does LeetCode 1342. Number of Steps to Reduce a Number to Zero cover?

LeetCode 1342. Number of Steps to Reduce a Number to Zero is tagged Bit Manipulation and Math on LeetCode.

EasyNo. 1342

Number of Steps to Reduce a Number to Zero — LeetCode 1342 Python Solution

Pattern: Bit Manipulation
Topics: Bit Manipulation, Math
Reading time: 2 min
Source: leetcode.com

The problem

Given an integer num, return the number of steps to reduce it to zero. In one step, if the current number is even, you have to divide it by 2, otherwise, you have to subtract 1 from it.

Example

Input: num = 14
Output: 6
Explanation: Step 1) 14 is even; divide by 2 and obtain 7.

Python solution

PythonSolution

class Solution:
    def numberOfSteps(self, num: int) -> int:
        ans = 0
        while num:
            if num & 1:
                num -= 1
            else:
                num >>= 1
            ans += 1
        return ans

Complexity

Time: O(n)
Space · auxiliary: O(1)

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 1342. Number of Steps to Reduce a Number to Zero is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

Related problems
No.	Problem	Difficulty
0029	Divide Two Integers	Medium
0067	Add Binary	Easy
0231	Power of Two	Easy
0342	Power of Four	Easy
0371	Sum of Two Integers	Medium
0405	Convert a Number to Hexadecimal	Easy

Frequently asked questions

How hard is LeetCode 1342. Number of Steps to Reduce a Number to Zero?: LeetCode 1342. Number of Steps to Reduce a Number to Zero is rated Easy on LeetCode.
What is the time complexity of LeetCode 1342. Number of Steps to Reduce a Number to Zero?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 1342. Number of Steps to Reduce a Number to Zero?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 1342. Number of Steps to Reduce a Number to Zero cover?: LeetCode 1342. Number of Steps to Reduce a Number to Zero is tagged Bit Manipulation and Math on LeetCode.

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python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

Technical interview · 45 minsolution.pyShared editor · Python 3Longest substring without repeatsMediumGiven a string s, return the length of the longest contiguous substring in which every character is unique.s = "abcabcbb"
→ 31def length_of_longest_substring(s: str) -> int:2 last_seen = {}3 left = best = 04 for right, ch in enumerate(s):5 if ch in last_seen and last_seen[ch] >= left:

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

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Transcribing...

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python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

Primary display

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

The problem

Example

Python solution

Complexity

Pattern: Bit Manipulation

Related problems

Frequently asked questions

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Approach

Approach

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