Java · Coding problem

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A free coding problem from the Java: Numbers, Bits and Strings skill. Read it here, then solve it in the app in Java.

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  • Java

The problem

A chat app in Dublin shows a short preview of each new message in the phone's notification. The preview is at most n characters long:

  • If the message has n characters or fewer, show the whole message.
  • Otherwise show its first n characters followed by ....

A "character" here means what the reader sees as one symbol, so Hi 👋 has 4 characters. Messages can contain emoji, and an emoji must never be cut in half. (The tests use single-code-point emoji only, with no skin tones, flags or joined emoji. The deep dive explains those.)

Example

Input:  n = 10, message = See you at 6 in Austin
Output: See you at...

Input: n on the first line, the message on the second. Output: the preview.

Constraints

  • 1 <= n <= 1000
  • the message is 1 to 1000 characters, with no leading or trailing spaces

How it's graded

  • Run checks your code against the examples. Submit also runs hidden tests, and you see pass or fail for them, never their inputs.
  • Stuck? Hints come in four steps, from a nudge to a code skeleton, each costing part of the points.
  • Once you pass, you see the approaches from brute force to optimal, and where your solution lands among them.

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