0881._Boats_to_Save_People

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881. Boats to Save People

难度: Medium

刷题内容

原题连接

内容描述

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The i-th person has weight people[i], and each boat can carry a maximum weight of limit.

Each boat carries at most 2 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.  (It is guaranteed each person can be carried by a boat.)

 

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)
Note:

1 <= people.length <= 50000
1 <= people[i] <= limit <= 30000

解题方案

思路 1
**- 时间复杂度: O(N logN)**- 空间复杂度: O(N)**

  • 使用贪心算法，将数组进行排序之后进行处理

代码：

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/**
 * @param {number[]} people
 * @param {number} limit
 * @return {number}
 */
var numRescueBoats = function(people, limit) {
    people.sort(function (a,b) { return a-b });
    var num=0;
    for(var left = 0,right = people.length-1;right-left>=0;right--){
        if(people[left]+people[right]<=limit)
            left++;
        num++;
    }
    return num;
};