Write It in Another Base

EasyMath & Geometry

Problem

A debugging console shows integers in any base from 2 to 36. Digits above 9 are written with lowercase letters: a = 10, b = 11, ..., z = 35.

Given an integer value and a base, return value written in that base. Negative values start with -. Zero is written "0".

Example 1

Input:
value = 255, base = 16
Output:
"ff"

255 = 15 · 16 + 15.

Example 2

Input:
value = -10, base = 2
Output:
"-1010"

Example 3

Input:
value = 0, base = 7
Output:
"0"

Constraints

  • -10^15 ≤ value ≤ 10^15
  • 2 ≤ base ≤ 36

Hint

Show the first hint

The last digit of value in base b is value mod b.

Walkthrough

How to approach it

01Clarify before coding

  • Uppercase or lowercase letters? Lowercase, a = 10 up to z = 35.
  • How are negatives shown? A leading minus sign on the magnitude, not two's complement.
  • Can I use a built-in such as toString(base)? No: write the conversion yourself.

02Brute force

Find the largest power of the base not exceeding value, then subtract multiples of each power from the top down.

Cost: Also O(log_b |value|), but computing powers risks overflow and is easy to get wrong; repeated division is simpler.

The rest of the walkthrough is in the app

The full walkthrough (key insight, step-by-step, dry run, complexity, edge cases, pitfalls, follow-ups) and solutions in Python and JavaScript are in the app, next to an editor and a terminal that runs your code against the tests.

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This problem is part of Pro.