Project Notes

Triangle

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Description

tab: English
 
<p>Given a <code>triangle</code> array, return <em>the minimum path sum from top to bottom</em>.</p>
 
<p>For each step, you may move to an adjacent number of the row below. More formally, if you are on index <code>i</code> on the current row, you may move to either index <code>i</code> or index <code>i + 1</code> on the next row.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
 
<pre>
<strong>Input:</strong> triangle = [[2],[3,4],[6,5,7],[4,1,8,3]]
<strong>Output:</strong> 11
<strong>Explanation:</strong> The triangle looks like:
   <u>2</u>
  <u>3</u> 4
 6 <u>5</u> 7
4 <u>1</u> 8 3
The minimum path sum from top to bottom is 2 + 3 + 5 + 1 = 11 (underlined above).
</pre>
 
<p><strong class="example">Example 2:</strong></p>
 
<pre>
<strong>Input:</strong> triangle = [[-10]]
<strong>Output:</strong> -10
</pre>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li><code>1 &lt;= triangle.length &lt;= 200</code></li>
	<li><code>triangle[0].length == 1</code></li>
	<li><code>triangle[i].length == triangle[i - 1].length + 1</code></li>
	<li><code>-10<sup>4</sup> &lt;= triangle[i][j] &lt;= 10<sup>4</sup></code></li>
</ul>
 
<p>&nbsp;</p>
<strong>Follow up:</strong> Could you&nbsp;do this using only <code>O(n)</code> extra space, where <code>n</code> is the total number of rows in the triangle?
 
 
---
 
[submissions](https://leetcode.com/problems/triangle/submissions/) | [solutions](https://leetcode.com/problems/triangle/solutions/)
 
 
tab: 中文
 
<p>给定一个三角形 <code>triangle</code> ，找出自顶向下的最小路径和。</p>
 
<p>每一步只能移动到下一行中相邻的结点上。<strong>相邻的结点 </strong>在这里指的是 <strong>下标</strong> 与 <strong>上一层结点下标</strong> 相同或者等于 <strong>上一层结点下标 + 1</strong> 的两个结点。也就是说，如果正位于当前行的下标 <code>i</code> ，那么下一步可以移动到下一行的下标 <code>i</code> 或 <code>i + 1</code> 。</p>
 
<p> </p>
 
<p><strong>示例 1：</strong></p>
 
<pre>
<strong>输入：</strong>triangle = [[2],[3,4],[6,5,7],[4,1,8,3]]
<strong>输出：</strong>11
<strong>解释：</strong>如下面简图所示：
   <strong>2</strong>
  <strong>3</strong> 4
 6 <strong>5</strong> 7
4 <strong>1</strong> 8 3
自顶向下的最小路径和为 11（即，2 + 3 + 5 + 1 = 11）。
</pre>
 
<p><strong>示例 2：</strong></p>
 
<pre>
<strong>输入：</strong>triangle = [[-10]]
<strong>输出：</strong>-10
</pre>
 
<p> </p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 <= triangle.length <= 200</code></li>
	<li><code>triangle[0].length == 1</code></li>
	<li><code>triangle[i].length == triangle[i - 1].length + 1</code></li>
	<li><code>-10<sup>4</sup> <= triangle[i][j] <= 10<sup>4</sup></code></li>
</ul>
 
<p> </p>
 
<p><strong>进阶：</strong></p>
 
<ul>
	<li>你可以只使用 <code>O(n)</code> 的额外空间（<code>n</code> 为三角形的总行数）来解决这个问题吗？</li>
</ul>
 
 
 
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[提交记录](https://leetcode.cn/problems/triangle/submissions/) | [题解](https://leetcode.cn/problems/triangle/solution/)

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