Boats to save people

Array Two Pointers Greedy Sorting

61.4% acceptance

Feb 22, 2026

6900

178

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.

Solution

Rust

Time O(n log n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn num_rescue_boats(mut people: Vec<i32>, limit: i32) -> i32 {
    people.sort_unstable();
    let mut lo = 0i32;
    let mut hi = people.len() as i32 - 1;
    let mut boats = 0;
    while lo <= hi {
      if people[lo as usize] + people[hi as usize] <= limit { lo += 1; }
      hi -= 1;
      boats += 1;
    }
    boats
  }
}