Is Thousand Separator easy or hard?

Thousand Separator is classified as an Easy problem. The challenge focuses on careful string formatting and handling digit grouping correctly rather than complex algorithms or data structures.

Thousand Separator Python/Java solution

Both Python and Java solutions typically convert the integer to a string and iterate from right to left, inserting a dot after every three digits. Python can also use regex replacement, while Java often uses StringBuilder for efficient string construction.

How to solve Thousand Separator in O(n)?

Convert the integer to a string, iterate from the last character to the first, and insert a dot after every third digit while constructing the result. Using a buffer or StringBuilder keeps the process efficient. After processing all digits, reverse the result if you built it backward.

What is the best approach for Thousand Separator?

The most reliable approach is processing the number as a string from right to left and inserting a dot after every three digits. This runs in O(n) time and O(n) space where n is the number of digits. It avoids complex index calculations and works consistently in languages like C++, Java, Python, and JavaScript.

Is Thousand Separator asked at Google/Amazon/Meta?

This problem is categorized as an easy string formatting task and appears mainly in practice sets or screening rounds. While not among the most frequently reported interview questions at Google or Meta, it reflects common string manipulation patterns that appear in real interview questions.

What data structure is used in Thousand Separator?

The solution primarily uses strings and sometimes a mutable buffer such as StringBuilder, list, or character array to build the formatted result efficiently. No advanced data structures are required.

What is the time complexity of Thousand Separator?

The optimal solution runs in O(n) time because each digit of the number is processed exactly once. Space complexity is O(n) since the algorithm builds a new formatted string containing digits and separator characters.

Description Hints 1 Solution Video 25:36

1556. Thousand Separator

Easy53.7% acceptance

Given an integer n, add a dot (".") as the thousands separator and return it in string format.

Example 1:

Input: n = 987
Output: "987"

Example 2:

Input: n = 1234
Output: "1.234"

Constraints:

0 <= n <= 2³¹ - 1

Topics

String

Hints open one at a time

Hint 1

Scan from the back of the integer and use dots to connect blocks with length 3 except the last block.

25:36

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Solution:
2    def thousandSeparator(self, n: int) -> str:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

Your code is saved on this device.Solution