Clarify the encryption scheme (e.g., Caesar cipher) and edge cases, then implement decryption by shifting each character backward by the key. Discuss time and space complexity and consider optimizations like handling large keys with modulo.
Pro tip: Demonstrate thoroughness by asking about the character set (e.g., only lowercase letters) and whether the shift can be negative or larger than the alphabet size, showing attention to detail and robustness.
Ask questions to confirm the encryption method, character set, and constraints (e.g., shift range, case sensitivity).
Explain that decryption reverses the shift: for each character, compute its original position by subtracting the key, handling wrap-around with modulo.
Discuss how to handle non-alphabetic characters, negative shifts, and keys larger than the alphabet size (using modulo).
Write clean code (or pseudocode) and walk through examples, including edge cases, to verify correctness.
State that the solution is O(n) time and O(1) extra space (if modifying in place) or O(n) space for the output string.
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