mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-01-10 18:48:13 +08:00
49 lines
1.2 KiB
HTML
49 lines
1.2 KiB
HTML
<p>Given an array of positive integers <code>arr</code>, return <em>the sum of all possible <strong>odd-length subarrays</strong> of </em><code>arr</code>.</p>
|
|
|
|
<p>A <strong>subarray</strong> is a contiguous subsequence of the array.</p>
|
|
|
|
<p> </p>
|
|
<p><strong class="example">Example 1:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> arr = [1,4,2,5,3]
|
|
<strong>Output:</strong> 58
|
|
<strong>Explanation: </strong>The odd-length subarrays of arr and their sums are:
|
|
[1] = 1
|
|
[4] = 4
|
|
[2] = 2
|
|
[5] = 5
|
|
[3] = 3
|
|
[1,4,2] = 7
|
|
[4,2,5] = 11
|
|
[2,5,3] = 10
|
|
[1,4,2,5,3] = 15
|
|
If we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58</pre>
|
|
|
|
<p><strong class="example">Example 2:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> arr = [1,2]
|
|
<strong>Output:</strong> 3
|
|
<b>Explanation: </b>There are only 2 subarrays of odd length, [1] and [2]. Their sum is 3.</pre>
|
|
|
|
<p><strong class="example">Example 3:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> arr = [10,11,12]
|
|
<strong>Output:</strong> 66
|
|
</pre>
|
|
|
|
<p> </p>
|
|
<p><strong>Constraints:</strong></p>
|
|
|
|
<ul>
|
|
<li><code>1 <= arr.length <= 100</code></li>
|
|
<li><code>1 <= arr[i] <= 1000</code></li>
|
|
</ul>
|
|
|
|
<p> </p>
|
|
<p><strong>Follow up:</strong></p>
|
|
|
|
<p>Could you solve this problem in O(n) time complexity?</p>
|