LeetCode

LeetCode 2106 note: the harvest is always a contiguous block of fruits; covering [L, R] takes (R - L) + min(|start - L|, |R - start|) steps, so slide a window over the fruits array

LeetCode 3805 note: shift each string so its first letter is a, making Caesar-equivalent strings identical, then count pairs per normalized form

LeetCode 3804 note: fix the left end and extend right, adding to the sum and to a set; count the subarray when the sum is in the set

LeetCode 3803 note: add characters to a set while scanning; count a prefix when its distinct count equals its length % 3

LeetCode 2831 note: list the positions of each value and slide a window over that list; the deletions needed are the span of positions minus the number of copies

LeetCode 2779 note: each number can become anything in [x - k, x + k], so a group can become one value ⇔ max - min <= 2k; sort and find the longest such window

LeetCode 2730 note: the window holds at most one adjacent equal pair; when a new pair arrives, shrink the left until the previous pair leaves

LeetCode 2516 note: taking from both ends leaves a middle block in which each letter may appear at most total − k times; find the longest such window

LeetCode 2271 note: starting the carpet at some segment’s start is never worse; after sorting, two pointers sum the fully covered segments and count the last one partially

LeetCode 1838 note: after sorting, raising the whole window to nums[right] costs nums[right] × length − window sum; shrink the left while that exceeds k

LeetCode 1458 note: a two-prefix DP; dp[i][j] either pairs nums1[i] with nums2[j] (extending dp[i-1][j-1] or starting fresh) or skips one of them

LeetCode 3634 note: after sorting, what remains is always a contiguous block; for each minimum nums[left], a right-only pointer finds how far it can extend, and everything outside is removed