LeetCode

LeetCode 3684 note: all values are positive, so deduplicate and take the k largest in descending order

LeetCode 3555 note: every length-k window is one instance of LeetCode 581; with n only 1000, two O(k) scans per window are enough

LeetCode 2273 note: repeatedly deleting a word that is an anagram of the previous one keeps exactly the words that are not anagrams of the last kept word; compare sorted strings

LeetCode 1793 note: expand from k toward the larger neighbor each step so the minimum stays as large as possible for each length; at a boundary, only the other side can grow

LeetCode 3323 note: merge first; a new interval can join groups l through r ⇔ start of group r − end of group l <= k, so a sliding window finds the most groups one interval can connect

LeetCode 1989 note: process the “it” players left to right, each catching the leftmost uncaught person in range, with a right-only pointer to the next candidate

LeetCode 2972 note: what remains is a strictly increasing prefix plus suffix; for each valid prefix end, a right-only pointer finds the first suffix start that can follow it, and every later start works too

LeetCode 2122 note: the smallest number is always in lower, so enumerating its partner fixes k; after sorting, two pointers pair each smallest unmatched number with the number 2k above it

LeetCode 1984 note: after sorting, the chosen k scores are always contiguous; slide a fixed window of length k and subtract its ends

LeetCode 658 note: shrink two pointers from both ends to length k, or binary search the window start

LeetCode 633 note: converge a from 0 and b from isqrt(c); shrink b when the sum is too big and grow a when it is too small; watch for 0, a == b, and floating-point square roots

LeetCode 3820 note: three BFS runs give every node’s distance to the three targets