LeetCode

LeetCode 1888 note: rotations become length-n windows over s + s; the window’s mismatches against 0101… are diff, and against 1010… they are n - diff

LeetCode 3788 note: build the suffix minimum first, then accumulate the prefix sum from the left and try every split

LeetCode 3694 note: the endpoint is the total displacement minus the removed segment’s displacement; a length-k window tracks that segment and each endpoint goes into a set

LeetCode 2134 note: the 1s end up in a circular window as long as their count, and the swaps needed equal the 0s in that window; slide around the circle for the minimum

LeetCode 3679 note: the rule already decides what must be discarded, so simulate it; the length-w window counts only kept arrivals, and discarded ones must not be subtracted when they leave

LeetCode 2461 note: in a fixed window of length k, all values are distinct exactly when the number of distinct values equals k

LeetCode 1423 note: taking k cards from the ends leaves a contiguous middle of n - k cards; find its minimum sum with a fixed-size window

LeetCode 584 note: referee_id != 2 misses NULLs, since comparing with NULL is unknown; add IS NULL explicitly

LeetCode 2841 note: a fixed window of length k keeps a sum and a count map; the number of distinct values is the map’s size, so delete keys that drop to zero

LeetCode 1757 note: both conditions must hold, so filter with WHERE … AND …

LeetCode 1281 note: walk the digits once, accumulating product and sum, and return product minus sum

LeetCode 1512 note: count while scanning; each number pairs with every earlier equal number, so add its current count to the answer