1695. Maximum Erasure Value

# 1695. Maximum Erasure Value#

## 题目 #

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 #

• 读完题立马能识别出这是经典的滑动窗口题。利用滑动窗口从左往右滑动窗口，滑动过程中统计频次，如果是不同元素，右边界窗口又移，否则左边窗口缩小。每次移动更新 max 值。最终扫完一遍以后，max 值即为所求。

## 代码 #

``````package leetcode

func maximumUniqueSubarray(nums []int) int {
if len(nums) == 0 {
return 0
}
result, left, right, freq := 0, 0, -1, map[int]int{}
for left < len(nums) {
if right+1 < len(nums) && freq[nums[right+1]] == 0 {
freq[nums[right+1]]++
right++
} else {
freq[nums[left]]--
left++
}
sum := 0
for i := left; i <= right; i++ {
sum += nums[i]
}
result = max(result, sum)
}
return result
}

func max(a int, b int) int {
if a > b {
return a
}
return b
}
``````

Apr 8, 2023