Leetcode Series. No 881: Boats to Save People

Max Tsogt
1 min readMar 24, 2022

You are given an array people where people[i] is the weight of the ith person, and an infinite number of boats where each boat can carry a maximum weight of limit. Each boat carries at most two people at the same time, provided the sum of the weight of those people is at most limit.

Return the minimum number of boats to carry every given person.

Example 1:

Input: people = [1,2], limit = 3
Output: 1
Explanation: 1 boat (1, 2)

Example 2:

Input: people = [3,2,2,1], limit = 3
Output: 3
Explanation: 3 boats (1, 2), (2) and (3)

Example 3:

Input: people = [3,5,3,4], limit = 5
Output: 4
Explanation: 4 boats (3), (3), (4), (5)

As always, follow the comments for each line.

This solution takes O( N log (N)) for time complexity and as for space complexity, it is O(N).

From my comments on the code, if you have any questions or comments, feel free to reach out.

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