How should I practice Format a Signed Integer with Commas?

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Problem · String

Format a Signed Integer with Commas

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● Easy

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Problem statement

Given a signed integer value, return its base-10 representation with a comma between every group of three digits, counting from the right.

Keep a leading minus sign before all digits. Do not add leading zeros or a plus sign.

Function

formatWithCommas(value: int) → String

Examples

Example 1

value = 1234return = "1,234"

Reading from the right, the final three digits form one group, so one comma precedes 234.

Example 2

value = -9876543return = "-9,876,543"

The magnitude is split into 9, 876, and 543; the minus sign remains at the front.

Example 3

value = 0return = "0"

A one-digit value needs no separator.

Constraints

-2^31 <= value <= 2^31 - 1.
The result contains only decimal digits, comma separators, and an optional leading minus sign.