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Start by clarifying the problem constraints (distinct numbers, range [0, n], exactly one missing). Then present the optimal solution using the sum formula: compute the expected sum of 0 to n and subtract the actual sum of the array. Mention alternative approaches like XOR or sorting, but highlight the sum method as O(n) time and O(1) space.
Pro tip: Always discuss trade-offs: the sum method can overflow for large n, so mention XOR as a safer alternative. Also, show awareness of edge cases like n=0 or missing number being 0 or n.
Confirm that the array contains n distinct numbers from 0 to n, with exactly one missing. Ask about constraints like input size or memory limits.
Explain that the sum of numbers from 0 to n is n*(n+1)/2. Subtract the sum of the array to get the missing number.
State that this approach runs in O(n) time and O(1) space, which is optimal for this problem.
Mention XOR-based solution (avoids overflow) and sorting (O(n log n)). Compare their pros and cons.
Consider cases like n=0, missing number is 0 or n, and potential integer overflow for large n.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.