Boats to Save People

Sort the weights. Let left be the lightest remaining person and right the heaviest. The heaviest person must leave in the next boat because pairing two lighter people does not remove that unavoidable need. If people[left] + people[right] <= limit, pair them and advance both pointers. Otherwise the heaviest cannot pair with even the lightest remaining person, so send the heaviest alone and decrement only right. Count one boat per iteration. This greedy choice never harms a future pairing: when a pair is possible, using the lightest companion preserves heavier people for other boats; when it is impossible, no companion can fit. Sorting takes O(n log n), the scan is O(n), and extra space depends on sorting. The problem's at-most-two-people rule is essential; larger boat capacities lead to a different packing problem.