Sliding-Window

LeetCode 3298 note: rearrangeable to start with word2 ⇔ every character count is at least word2’s; an “at least” counting window where meet tracks how many characters have reached their target

LeetCode 2537 note: adding x creates cnt[x] new equal pairs and removing it loses cnt[x] - 1; an “at least k pairs” counting window with count += left

LeetCode 3325 note: an “at least one character appears k times” counting window; when the new character reaches k, keep shrinking until it drops to k - 1

LeetCode 2962 note: an “at least k” counting window: keep shrinking while the max appears k times, after which every left end in [0, left) is valid, so count += left

LeetCode 2762 note: a sliding window with two monotonic queues for the window maximum and minimum

LeetCode 1358 note: an “at least one each of a, b, c” counting window: keep shrinking while all three are present, then count += left

LeetCode 632 note: a heap of each list’s current element plus the running maximum; always advance the smallest

LeetCode 3258 note: valid means zeros <= k or ones <= k; it is invalid only when both exceed k, and after shrinking there are right - left + 1 valid substrings ending at right

LeetCode 2968 note: after sorting, the cheapest common target for a block is its median; prefix sums give the cost in O(1), and it grows with the window, so slide

LeetCode 2904 note: with exactly k ones in the window, also shrink away leading zeros to get the shortest beautiful substring ending at right; compare by length first, then lexicographically

LeetCode 2875 note: strip target // sum full cycles; the remainder is smaller than one cycle, so a sliding window over two copies of nums always finds it

LeetCode 2302 note: score = sum × length with positive numbers grows with the window; shrink while the score is >= k, and right - left + 1 valid subarrays end at right