leetcode-problemset/leetcode-cn/problem (Chinese)/变长子数组求和 [sum-of-variable-length-subarrays].html

<p>给你一个长度为 <code>n</code>&nbsp;的整数数组&nbsp;<code>nums</code>&nbsp;。对于 <strong>每个</strong> 下标&nbsp;<code>i</code>（<code>0 &lt;= i &lt; n</code>），定义对应的子数组&nbsp;<code>nums[start ... i]</code>（<code>start = max(0, i - nums[i])</code>）。</p>

<p>返回为数组中每个下标定义的子数组中所有元素的总和。</p>
<strong>子数组</strong>&nbsp;是数组中的一个连续、<strong>非空</strong> 的元素序列。

<p>&nbsp;</p>

<p><b>示例 1：</b></p>

<div class="example-block">
<p><b>输入：</b><span class="example-io">nums = [2,3,1]</span></p>

<p><span class="example-io"><b>输出：</b>11</span></p>

<p><b>解释：</b></p>

<table style="border: 1px solid black;">
	<tbody>
		<tr>
			<th style="border: 1px solid black;">下标 i</th>
			<th style="border: 1px solid black;">子数组</th>
			<th style="border: 1px solid black;">和</th>
		</tr>
		<tr>
			<td style="border: 1px solid black;">0</td>
			<td style="border: 1px solid black;"><code>nums[0] = [2]</code></td>
			<td style="border: 1px solid black;">2</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;">1</td>
			<td style="border: 1px solid black;"><code>nums[0 ... 1] = [2, 3]</code></td>
			<td style="border: 1px solid black;">5</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;">2</td>
			<td style="border: 1px solid black;"><code>nums[1 ... 2] = [3, 1]</code></td>
			<td style="border: 1px solid black;">4</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;"><b>总和</b></td>
			<td style="border: 1px solid black;">&nbsp;</td>
			<td style="border: 1px solid black;">11</td>
		</tr>
	</tbody>
</table>

<p>总和为 11 。因此，输出 11 。</p>
</div>

<p><b>示例 2：</b></p>

<div class="example-block">
<p><span class="example-io"><b>输入：</b>nums = [3,1,1,2]</span></p>

<p><span class="example-io"><b>输出：</b>13</span></p>

<p><b>解释：</b></p>

<table style="border: 1px solid black;">
	<tbody>
		<tr>
			<th style="border: 1px solid black;">下标 i</th>
			<th style="border: 1px solid black;">子数组</th>
			<th style="border: 1px solid black;">和</th>
		</tr>
		<tr>
			<td style="border: 1px solid black;">0</td>
			<td style="border: 1px solid black;"><code>nums[0] = [3]</code></td>
			<td style="border: 1px solid black;">3</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;">1</td>
			<td style="border: 1px solid black;"><code>nums[0 ... 1] = [3, 1]</code></td>
			<td style="border: 1px solid black;">4</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;">2</td>
			<td style="border: 1px solid black;"><code>nums[1 ... 2] = [1, 1]</code></td>
			<td style="border: 1px solid black;">2</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;">3</td>
			<td style="border: 1px solid black;"><code>nums[1 ... 3] = [1, 1, 2]</code></td>
			<td style="border: 1px solid black;">4</td>
		</tr>
		<tr>
			<td style="border: 1px solid black;"><b>总和</b></td>
			<td style="border: 1px solid black;">&nbsp;</td>
			<td style="border: 1px solid black;">13</td>
		</tr>
	</tbody>
</table>

<p>总和为 13 。因此，输出为 13 。</p>
</div>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>1 &lt;= n == nums.length &lt;= 100</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 1000</code></li>
</ul>