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✨ topic

⭐

  1. Sort an array

  2. Greed + double pointer

🌈 Case Explanation

Take case 3 for example

Sort the array by:3, 5-tetrafluorobenzoic.limit = 5

Maintaining dual PointersLeft = 0, right = people. Length - 1

Cyclic conditions:left <= rightBecause, whenleft == rightWhen, there was still one person who needed to make the boat, so it could not be usedleft < right


Case 3 might not be obvious, so let’s do case 2 again

Sort the array by:1,2,2,3.limit = 3

Why is it left++, because they say a boat can’t do more than two people

🔥 code implementation

class Solution {
    public int numRescueBoats(int[] people, int limit) {
    
        Arrays.sort(people);
        int len = people.length;
        int left = 0, right = len - 1;

        int res = 0;

        while (left <= right) {
        	// If people[left] + people[right] <= limit, leave ++
        	// It is greedy to make the boat as crowded as possible
            if (people[left] + people[right] <= limit) {
                ++left;
            }
            --right;
            ++res;
        }
        returnres; }}Copy the code

💖 finally

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