1582 articles
LeetCode 268 Missing Number: find the one missing integer in [0..n] using XOR cancellation or the Gauss arithmetic-series formula. Two O(n) techniques every FAANG interviewer expects you to compare.
LeetCode 371 Sum of Two Integers: add integers using only XOR and AND. Master the half-adder, carry propagation, and two's complement trick that reveals how CPUs actually compute sums.
LeetCode 78 Subsets: enumerate the power set with bitmask iteration. Master the elegant 2^n bit-loop FAANG interviewers prefer over recursion for its clarity and speed.
LeetCode 698 Partition to K Equal Sum Subsets: decide if an array can be split into k equal-sum buckets. Master the bitmask DP that converts an exponential DFS into a clean O(2^n * n) solution loved by FAANG interviewers.
LeetCode 477 Total Hamming Distance: sum bit-differences across every pair in linear time. Master the per-bit contribution trick that turns O(n^2) brute force into O(n) — a FAANG favorite.