Array

LeetCode 3904 note: the first index where the prefix maximum minus the suffix minimum is <= k; build the suffix minimum right to left first

LeetCode 3903 note: the first index where the prefix maximum minus the suffix minimum is <= k; build the suffix minimum right to left first

LeetCode 3898 note: the number of ones in row i of the adjacency matrix is vertex i’s degree

LeetCode 522 note: the longest uncommon subsequence is always a whole string; check strings from longest to shortest, and the first that is not a subsequence of any other long-enough string is the answer

LeetCode 1826 note: at the first mismatch, test both “who dropped a value” explanations; if both fit, it cannot be determined, so return -1

LeetCode 3843 note: count each value, then count how many values share each count; the first element from the left whose count is its own is the answer

LeetCode 3842 note: toggle membership in a set, or keep bulbs appearing an odd number of times, then sort

LeetCode 3840 note: houses conflict only when adjacent with the same color; take a house outright when the colors differ, and do the House Robber choice only when they match

LeetCode 3838 note: sum each word’s letter weights mod 26 and map backward: 0 -> z, i.e. chr(ord(‘z’) - r)

LeetCode 3719 note: n is only 1500, so fix the left end and extend right, maintaining distinct odds and evens in two sets

LeetCode 1570 note: store only non-zero (index, value) pairs, and compute the dot product by merging the two index-sorted lists with two pointers, multiplying only on equal indices

LeetCode 1229 note: sort both people’s slots, then find intersections with two pointers as in 986; the first intersection that is long enough is the earliest slot