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74 lines
2.0 KiB
Markdown
74 lines
2.0 KiB
Markdown
# [1695. Maximum Erasure Value](https://leetcode.com/problems/maximum-erasure-value/)
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## 题目
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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.
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Return *the **maximum score** you can get by erasing **exactly one** subarray.*
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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)`.
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**Example 1:**
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```
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Input: nums = [4,2,4,5,6]
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Output: 17
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Explanation: The optimal subarray here is [2,4,5,6].
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```
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**Example 2:**
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```
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Input: nums = [5,2,1,2,5,2,1,2,5]
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Output: 8
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Explanation: The optimal subarray here is [5,2,1] or [1,2,5].
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```
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**Constraints:**
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- `1 <= nums.length <= 105`
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- `1 <= nums[i] <= 104`
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## 题目大意
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给你一个正整数数组 nums ，请你从中删除一个含有 若干不同元素 的子数组。删除子数组的 得分 就是子数组各元素之 和 。返回 只删除一个 子数组可获得的 最大得分 。如果数组 b 是数组 a 的一个连续子序列，即如果它等于 a[l],a[l+1],...,a[r] ，那么它就是 a 的一个子数组。
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## 解题思路
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- 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。
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## 代码
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```go
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package leetcode
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func maximumUniqueSubarray(nums []int) int {
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if len(nums) == 0 {
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return 0
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}
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result, left, right, freq := 0, 0, -1, map[int]int{}
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for left < len(nums) {
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if right+1 < len(nums) && freq[nums[right+1]] == 0 {
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freq[nums[right+1]]++
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right++
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} else {
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freq[nums[left]]--
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left++
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}
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sum := 0
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for i := left; i <= right; i++ {
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sum += nums[i]
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}
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result = max(result, sum)
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}
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return result
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}
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func max(a int, b int) int {
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if a > b {
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return a
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}
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return b
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}
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``` |