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How to Solve Count Numbers with Non-Decreasing Digits Problem
Master the Count Numbers with Non-Decreasing Digits LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsHard#3519
LeetCode ProblemCount Numbers with Non-Decreasing Digits
You are given two integers, l and r, represented as strings, and an integer b. Return the count of integers in the inclusive range [l, r] whose digits are in non-decreasing order when represented in base b. An integer is considered to have non-decreasing digits if, when read from left to right (from the most significant digit to the least significant digit), each digit is greater than or equal to the previous one. Since the answer may be too large, return it modulo 109 + 7.
MathStringDynamic Programming
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Problem Breakdown
Understanding the Count Numbers with Non-Decreasing Digits Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
You are given two integers, l and r, represented as strings, and an integer b. Return the count of integers in the inclusive range [l, r] whose digits are in non-decreasing order when represented in base b. An integer is considered to have non-decreasing digits if, when read from left to right (from the most significant digit to the least significant digit), each digit is greater than or equal to the previous one. Since the answer may be too large, return it modulo 109 + 7.
HardProblem #3519
LeetCodeCount Numbers with Non-Decreasing Digits
Related Topics
MathStringDynamic Programming
How Phantom Code Helps
Get real-time assistance for Count Numbers with Non-Decreasing Digits problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
l = "23", r = "28", b = 8
Output
3
# Example 2
Input
l = "2", r = "7", b = 2
Output
2
Constraints
1 <= l.length <= r.length <= 100
2 <= b <= 10
l and r consist only of digits.
The value represented by l is less than or equal to the value represented by r.
l and r do not contain leading zeros.
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Solve Count Numbers with Non-Decreasing Digits — You are given two integers, l and r, represented as strings, and an integer b. R...
Here's the optimal approach using Math:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving Count Numbers with Non-Decreasing Digits and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Count Numbers with Non-Decreasing Digits during interviews?
Phantom Code generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Count Numbers with Non-Decreasing Digits ?
Phantom Code adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code help me communicate my solution for problems like Count Numbers with Non-Decreasing Digits ?
Yes. Phantom Code provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code assist with different programming languages for Count Numbers with Non-Decreasing Digits type problems?
Phantom Code supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code help me avoid during Count Numbers with Non-Decreasing Digits interviews?
Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code detectable when solving problems like Count Numbers with Non-Decreasing Digits during live interviews?
No. Phantom Code runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code help when I'm struggling with Count Numbers with Non-Decreasing Digits style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code work for the coding platforms used in Count Numbers with Non-Decreasing Digits interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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