Permutations with Self-Written Tests

Phone screen coding round equivalent to LC 46, with explicit expectation to clarify boundary cases and write test methods and test cases. Requirements Generate all permutations of the input array. Use DFS/backtracking. Clarify boundary cases from a short one-line prompt. Write test methods and test cases yourself. Notes Candidate identified the task as LC 46. The interviewer allowed online lookup for a backtracking template but explicitly said not to use AI. Prepare to explain duplicate handling if the interviewer changes the input from distinct values to repeated values.