881. Boats to Save People LeetCode Solution

In this guide, you will get 881. Boats to Save People LeetCode Solution with the best time and space complexity. The solution to Boats to Save People problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Boats to Save People solution in C++
Boats to Save People solution in Java
Boats to Save People solution in Python
Additional Resources

881. Boats to Save People LeetCode Solution image

Problem Statement of Boats to Save People

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)

Constraints:

1 <= people.length <= 5 * 104
1 <= people[i] <= limit <= 3 * 104

Complexity Analysis

Time Complexity: O(\texttt{sort})
Space Complexity: O(\texttt{sort})

881. Boats to Save People LeetCode Solution in C++

class Solution {
 public:
  int numRescueBoats(vector<int>& people, int limit) {
    int ans = 0;

    ranges::sort(people);

    for (int i = 0, j = people.size() - 1; i <= j; ++ans) {
      const int remain = limit - people[j--];
      if (people[i] <= remain)
        ++i;
    }

    return ans;
  }
};
/* code provided by PROGIEZ */

881. Boats to Save People LeetCode Solution in Java

class Solution {
  public int numRescueBoats(int[] people, int limit) {
    int ans = 0;

    Arrays.sort(people);

    for (int i = 0, j = people.length - 1; i <= j; ++ans) {
      final int remain = limit - people[j--];
      if (people[i] <= remain)
        ++i;
    }

    return ans;
  }
}
// code provided by PROGIEZ

881. Boats to Save People LeetCode Solution in Python

class Solution:
  def numRescueBoats(self, people: list[int], limit: int) -> int:
    ans = 0
    i = 0
    j = len(people) - 1

    people.sort()

    while i <= j:
      remain = limit - people[j]
      j -= 1
      if people[i] <= remain:
        i += 1
      ans += 1

    return ans
 # code by PROGIEZ