Create 881._Boats_to_Save_People.md

Author: Tang-DJ

docs/Leetcode_Solutions/JavaScript/881._Boats_to_Save_People.md

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+# 881. Boats to Save People
+
+**<font color=red>难度: Medium</font>**
+
+## 刷题内容
+
+> 原题连接
+
+* https://leetcode.com/problems/boats-to-save-people/description/
+
+> 内容描述
+
+```
+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(1)******- 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：
+
+```javascript
+/**
+ * @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;
+};
+```
+