【leetcode】1695. Maximum Erasure Value

题目如下：

You are given an array of positive integers nums and want to erase a subarray containing unique elements. The score you get by erasing the subarray is equal to the sum of its elements.

Return the maximum score you can get by erasing exactly one subarray.

An array b is called to be a subarray of a if it forms a contiguous subsequence of a, that is, if it is equal to a[l],a[l+1],...,a[r] for some (l,r).

Example 1:

Input: nums = [4,2,4,5,6]
Output: 17
Explanation: The optimal subarray here is [2,4,5,6].

Example 2:

Input: nums = [5,2,1,2,5,2,1,2,5]
Output: 8
Explanation: The optimal subarray here is [5,2,1] or [1,2,5].

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 104

解题思路：滑动窗口问题。从左往右依次遍历nums，并用字典保存出现的元素以及计算出这些元素的和。如果当前遍历到对应元素已经出现过，则在字典中删除最左边元素。

代码如下：

class Solution(object):
    def maximumUniqueSubarray(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        left = 0
        right = 0
        dic = {}
        res = 0
        amount = 0
        while right < len(nums):
            if nums[right] not in dic:
                dic[nums[right]] = 1
                amount += nums[right]
                right += 1
                res = max(res,amount)
            else:
                amount -= nums[left]
                del dic[nums[left]]
                left += 1
        return res