Project Notes

Path Sum

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Description

tab: English
 
<p>Given the <code>root</code> of a binary tree and an integer <code>targetSum</code>, return <code>true</code> if the tree has a <strong>root-to-leaf</strong> path such that adding up all the values along the path equals <code>targetSum</code>.</p>
 
<p>A <strong>leaf</strong> is a node with no children.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum1.jpg" style="width: 500px; height: 356px;" />
<pre>
<strong>Input:</strong> root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
<strong>Output:</strong> true
<strong>Explanation:</strong> The root-to-leaf path with the target sum is shown.
</pre>
 
<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum2.jpg" />
<pre>
<strong>Input:</strong> root = [1,2,3], targetSum = 5
<strong>Output:</strong> false
<strong>Explanation:</strong> There are two root-to-leaf paths in the tree:
(1 --&gt; 2): The sum is 3.
(1 --&gt; 3): The sum is 4.
There is no root-to-leaf path with sum = 5.
</pre>
 
<p><strong class="example">Example 3:</strong></p>
 
<pre>
<strong>Input:</strong> root = [], targetSum = 0
<strong>Output:</strong> false
<strong>Explanation:</strong> Since the tree is empty, there are no root-to-leaf paths.
</pre>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li>The number of nodes in the tree is in the range <code>[0, 5000]</code>.</li>
	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
	<li><code>-1000 &lt;= targetSum &lt;= 1000</code></li>
</ul>
 
 
 
---
 
[submissions](https://leetcode.com/problems/path-sum/submissions/) | [solutions](https://leetcode.com/problems/path-sum/solutions/)
 
 
tab: 中文
 
<p>给你二叉树的根节点&nbsp;<code>root</code> 和一个表示目标和的整数&nbsp;<code>targetSum</code> 。判断该树中是否存在 <strong>根节点到叶子节点</strong> 的路径，这条路径上所有节点值相加等于目标和&nbsp;<code>targetSum</code> 。如果存在，返回 <code>true</code> ；否则，返回 <code>false</code> 。</p>
 
<p><strong>叶子节点</strong> 是指没有子节点的节点。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例 1：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum1.jpg" style="width: 500px; height: 356px;" />
<pre>
<strong>输入：</strong>root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
<strong>输出：</strong>true
<strong>解释：</strong>等于目标和的根节点到叶节点路径如上图所示。
</pre>
 
<p><strong>示例 2：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/18/pathsum2.jpg" />
<pre>
<strong>输入：</strong>root = [1,2,3], targetSum = 5
<strong>输出：</strong>false
<strong>解释：</strong>树中存在两条根节点到叶子节点的路径：
(1 --&gt; 2): 和为 3
(1 --&gt; 3): 和为 4
不存在 sum = 5 的根节点到叶子节点的路径。</pre>
 
<p><strong>示例 3：</strong></p>
 
<pre>
<strong>输入：</strong>root = [], targetSum = 0
<strong>输出：</strong>false
<strong>解释：</strong>由于树是空的，所以不存在根节点到叶子节点的路径。
</pre>
 
<p>&nbsp;</p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li>树中节点的数目在范围 <code>[0, 5000]</code> 内</li>
	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
	<li><code>-1000 &lt;= targetSum &lt;= 1000</code></li>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/path-sum/submissions/) | [题解](https://leetcode.cn/problems/path-sum/solution/)

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