# 881. Boats to Save People

#### Medium

***

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`

```python
class Solution:
    def numRescueBoats(self, people: List[int], limit: int) -> int:
        people.sort()
        result = 0
        left = 0
        right = len(people)-1
        while left <= right:
            result += 1
            if people[left] + people[right] <= limit:
                left += 1
            right -= 1
        return result
                
```