The counting part was fine, just a frequency map and a scan.
First, clarify the input format and tie-breaking rules, then propose an efficient solution using a hash map to count votes and track the best candidate. Discuss time and space complexity, and consider edge cases such as empty input or mixed types.
Pro tip: Mention that you can combine counting and comparison in a single pass to avoid a second iteration, and explicitly state how you handle ties to show attention to detail.
Ask about input size, data types, and tie-breaking rules (lexicographical vs numerical). Confirm expected output for edge cases like empty array or all ties.
Use a hash map to count votes for each candidate. Maintain variables for the current winner and their count to avoid a second pass.
Iterate through votes, update counts, and compare with current winner. If count exceeds winner's count, update winner; if equal, apply tie-breaking rule.
State time complexity O(n) and space complexity O(k) where k is number of unique candidates. Discuss trade-offs if k is large.
Walk through examples: empty array, single candidate, tie between two, tie among many. Verify tie-breaking works as expected.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Start by explaining the Boyer-Moore voting algorithm: first pass finds a candidate by maintaining a count and switching candidates when count hits zero; second pass verifies if the candidate appears more than n/2 times. Emphasize that the algorithm guarantees a candidate if a majority exists, but verification is necessary to confirm. Then, walk through a concrete example to illustrate the process and discuss time/space complexity.
Pro tip: Mention that the algorithm can be extended to find elements appearing more than n/k times, showing deeper understanding. Also, note that the verification step is crucial because the candidate might not be the majority.
Clarify that the function should return the majority element (appearing > n/2 times) or null if none exists, with O(n) time and O(1) space. Confirm that the input is an array of votes (e.g., integers or strings).
Describe the two-phase approach: first, find a candidate by iterating through the array, maintaining a count and current candidate; second, verify the candidate's frequency by counting its occurrences.
Use a small array (e.g., [A, B, A, A, C, A]) to demonstrate how the candidate and count evolve, and how verification confirms A as the majority.
State that time complexity is O(n) (two passes) and space is O(1). Discuss edge cases: empty array, single element, no majority, and all elements same.
Write clean code with clear variable names, handling null/empty input, and returning null if no majority is found after verification.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.