Sliding-Window

LeetCode 1016 note: s has at most 1000 characters, so there are few substrings of any fixed length and a large n must be False; checking from n downward fails fast, or extend up to 30 bits from each start to collect every value <= n

LeetCode 3795 note: a shortest-window slide where each value counts once; track each value’s last position, and subtract the left value only if it was the last occurrence

LeetCode 2653 note: values are only -50 to 50, so the fixed window keeps a count array, and each window accumulates upward from -50 to find the x-th smallest negative

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 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 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 1493 note: find the longest window with at most one 0; since one element must be deleted, the answer is the window length minus 1

Sliding window over meetings; track total duration in a k-sized window and compute free span between boundaries.