FastPrep
Problem · String

Encode or Decode Message

● EasyGoldman SachsOA

Encodes or decodes a message using a shared numeric key.

Input

  • Operation:
    • 1 = Encode
    • 2 = Decode
  • Message (string)
  • Key (positive integer)

Encoding (Operation 1)

Duplicates each character based on the corresponding digit in the key.

Example:

Message: Open, Key: 123 → Output: Oppeen

Decoding (Operation 2)

Compresses repeated characters based on digits in the key.

Example:

Message: Oppeen, Key: 123 → Output: Open

Rules

  • Apply digits in key cyclically or until message ends.
  • Remaining characters (if key ends first) are left unchanged.
  • Return -1 for invalid input or mismatched patterns during decoding.

    • Examples
    01 · Example 1
    operation = 1
message = "Open"
key = 123
return = "Oppeen"
    ~~
    02 · Example 2
    operation = 2
message = "Oppeen"
key = 123
return = "Open"
    ~~~
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    public String encodeOrDecode(int operation, String message, int key) {
  // write your code here
}
    operation1
    message"Open"
    key123
    expected"Oppeen"
    checking account