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| 1 | +# 1800. Maximum Ascending Subarray Sum |
| 2 | + |
| 3 | +- Difficulty: Easy. |
| 4 | +- Related Topics: Array. |
| 5 | +- Similar Questions: Find Good Days to Rob the Bank, Maximum Number of Books You Can Take, Count Strictly Increasing Subarrays. |
| 6 | + |
| 7 | +## Problem |
| 8 | + |
| 9 | +Given an array of positive integers `nums`, return the **maximum possible sum of an **ascending** subarray in **`nums`. |
| 10 | + |
| 11 | +A subarray is defined as a contiguous sequence of numbers in an array. |
| 12 | + |
| 13 | +A subarray `[numsl, numsl+1, ..., numsr-1, numsr]` is **ascending** if for all `i` where `l <= i < r`, `numsi < numsi+1`. Note that a subarray of size `1` is **ascending**. |
| 14 | + |
| 15 | + |
| 16 | +Example 1: |
| 17 | + |
| 18 | +``` |
| 19 | +Input: nums = [10,20,30,5,10,50] |
| 20 | +Output: 65 |
| 21 | +Explanation: [5,10,50] is the ascending subarray with the maximum sum of 65. |
| 22 | +``` |
| 23 | + |
| 24 | +Example 2: |
| 25 | + |
| 26 | +``` |
| 27 | +Input: nums = [10,20,30,40,50] |
| 28 | +Output: 150 |
| 29 | +Explanation: [10,20,30,40,50] is the ascending subarray with the maximum sum of 150. |
| 30 | +``` |
| 31 | + |
| 32 | +Example 3: |
| 33 | + |
| 34 | +``` |
| 35 | +Input: nums = [12,17,15,13,10,11,12] |
| 36 | +Output: 33 |
| 37 | +Explanation: [10,11,12] is the ascending subarray with the maximum sum of 33. |
| 38 | +``` |
| 39 | + |
| 40 | + |
| 41 | +**Constraints:** |
| 42 | + |
| 43 | + |
| 44 | + |
| 45 | +- `1 <= nums.length <= 100` |
| 46 | + |
| 47 | +- `1 <= nums[i] <= 100` |
| 48 | + |
| 49 | + |
| 50 | + |
| 51 | +## Solution |
| 52 | + |
| 53 | +```javascript |
| 54 | +/** |
| 55 | + * @param {number[]} nums |
| 56 | + * @return {number} |
| 57 | + */ |
| 58 | +var maxAscendingSum = function(nums) { |
| 59 | + var maxSum = nums[0]; |
| 60 | + var currSum = nums[0]; |
| 61 | + for (var i = 1; i < nums.length; i++) { |
| 62 | + if (nums[i - 1] < nums[i]) { |
| 63 | + currSum += nums[i]; |
| 64 | + } else { |
| 65 | + maxSum = Math.max(maxSum, currSum); |
| 66 | + currSum = nums[i]; |
| 67 | + } |
| 68 | + } |
| 69 | + return Math.max(maxSum, currSum); |
| 70 | +}; |
| 71 | +``` |
| 72 | + |
| 73 | +**Explain:** |
| 74 | + |
| 75 | +nope. |
| 76 | + |
| 77 | +**Complexity:** |
| 78 | + |
| 79 | +* Time complexity : O(n). |
| 80 | +* Space complexity : O(1). |
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