# 904. Fruit Into Baskets

**<font color=red>难度: Medium</font>**

## 刷题内容

> 原题连接

* https://leetcode.com/contest/weekly-contest-102/problems/fruit-into-baskets/

> 内容描述

```
In a row of trees, the i-th tree produces fruit with type tree[i].

You start at any tree of your choice, then repeatedly perform the following steps:

Add one piece of fruit from this tree to your baskets.  If you cannot, stop.
Move to the next tree to the right of the current tree.  If there is no tree to the right, stop.
Note that you do not have any choice after the initial choice of starting tree: you must perform step 1, then step 2, then back to step 1, then step 2, and so on until you stop.

You have two baskets, and each basket can carry any quantity of fruit, but you want each basket to only carry one type of fruit each.

What is the total amount of fruit you can collect with this procedure?

 

Example 1:

Input: [1,2,1]
Output: 3
Explanation: We can collect [1,2,1].
Example 2:

Input: [0,1,2,2]
Output: 3
Explanation: We can collect [1,2,2].
If we started at the first tree, we would only collect [0, 1].
Example 3:

Input: [1,2,3,2,2]
Output: 4
Explanation: We can collect [2,3,2,2].
If we started at the first tree, we would only collect [1, 2].
Example 4:

Input: [3,3,3,1,2,1,1,2,3,3,4]
Output: 5
Explanation: We can collect [1,2,1,1,2].
If we started at the first tree or the eighth tree, we would only collect 4 fruits.
 

Note:

1 <= tree.length <= 40000
0 <= tree[i] < tree.length
```

## 解题方案

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



和第159一样的思路,时间复杂度最差为O(N)，因为有可能整个列表只有两种不同的数字

```python
class Solution(object):
    def totalFruit(self, A):
        """
        :type tree: List[int]
        :rtype: int
        """
        maps = {}
        begin, end, counter, res = 0, 0, 0, 0
        while end < len(A):
            maps[A[end]] = maps.get(A[end], 0) + 1
            if maps[A[end]] == 1:
                counter += 1
            end += 1  # end points to the next fruit
            while counter > 2:
                maps[A[begin]] -= 1
                if maps[A[begin]] == 0:
                    counter -= 1
                begin += 1
            res = max(res, end - begin)
        return res
```
