Array

LeetCode 3644 note: every misplaced number must be swapped, so each bit of k must belong to all of them; the answer is the AND of every misplaced number

Monotonic stack on a circular array

Monotonic decreasing stack over nums2 to build next-greater map; answer queries for nums1.

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

Sliding window with two pointers; minimize subarray length where sum ≥ target.

Sliding window with a set and running sum; two pointers to keep the subarray unique.

Remainder pairing with a hash map; handle 0 and k/2 remainders carefully.

LeetCode 2709 note: every pair of indices connects ⇔ one component; factor with SPF and union each number with its prime factors in Union-Find, treating 1 specially

LeetCode 135 note: one pass left to right for the left neighbor, one right to left for the right neighbor, and give each child the larger of the two

LeetCode 3638 note: greedily cut a segment as soon as a value below its maximum appears; until then the segment is non-decreasing, so its maximum is the previous value

LeetCode 3637 note: walk one index through uphill, downhill and uphill; all three runs must be non-empty and reach the end exactly

LeetCode Problem Solving - Reverse Thinking with Sliding Window