Boats to Save People — LeetCode 881 Python Solution

The problem

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.

Example

Input

people = [1,2], limit = 3

Output

1

Explanation

1 boat (1, 2)

Python solution

class Solution:
    def numRescueBoats(self, people: List[int], limit: int) -> int:
        people.sort()
        ans = 0
        i, j = 0, len(people) - 1
        while i <= j:
            if people[i] + people[j] <= limit:
                i += 1
            j -= 1
            ans += 1
        return ans

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 881. Boats to Save People is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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