Project Notes

Distinct Subsequences

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Description

tab: English
 
<p>Given two strings s and t, return <i>the number of distinct</i> <b><i>subsequences</i></b><i> of </i>s<i> which equals </i>t.</p>
 
<p>The test cases are generated so that the answer fits on a 32-bit signed integer.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
 
<pre>
<strong>Input:</strong> s = &quot;rabbbit&quot;, t = &quot;rabbit&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong>
As shown below, there are 3 ways you can generate &quot;rabbit&quot; from s.
<code><strong><u>rabb</u></strong>b<strong><u>it</u></strong></code>
<code><strong><u>ra</u></strong>b<strong><u>bbit</u></strong></code>
<code><strong><u>rab</u></strong>b<strong><u>bit</u></strong></code>
</pre>
 
<p><strong class="example">Example 2:</strong></p>
 
<pre>
<strong>Input:</strong> s = &quot;babgbag&quot;, t = &quot;bag&quot;
<strong>Output:</strong> 5
<strong>Explanation:</strong>
As shown below, there are 5 ways you can generate &quot;bag&quot; from s.
<code><strong><u>ba</u></strong>b<u><strong>g</strong></u>bag</code>
<code><strong><u>ba</u></strong>bgba<strong><u>g</u></strong></code>
<code><u><strong>b</strong></u>abgb<strong><u>ag</u></strong></code>
<code>ba<u><strong>b</strong></u>gb<u><strong>ag</strong></u></code>
<code>babg<strong><u>bag</u></strong></code></pre>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li><code>1 &lt;= s.length, t.length &lt;= 1000</code></li>
	<li><code>s</code> and <code>t</code> consist of English letters.</li>
</ul>
 
 
 
---
 
[submissions](https://leetcode.com/problems/distinct-subsequences/submissions/) | [solutions](https://leetcode.com/problems/distinct-subsequences/solutions/)
 
 
tab: 中文
 
<p>给你两个字符串 <code>s</code><strong> </strong>和 <code>t</code> ，统计并返回在 <code>s</code> 的 <strong>子序列</strong> 中 <code>t</code> 出现的个数。</p>
 
<p>测试用例保证结果在 32 位有符号整数范围内。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例&nbsp;1：</strong></p>
 
<pre>
<strong>输入：</strong>s = "rabbbit", t = "rabbit"<code>
<strong>输出</strong></code><strong>：</strong><code>3
</code><strong>解释：</strong>
如下所示, 有 3 种可以从 s 中得到 <code>"rabbit" 的方案</code>。
<code><strong><u>rabb</u></strong>b<strong><u>it</u></strong></code>
<code><strong><u>ra</u></strong>b<strong><u>bbit</u></strong></code>
<code><strong><u>rab</u></strong>b<strong><u>bit</u></strong></code></pre>
 
<p><strong>示例&nbsp;2：</strong></p>
 
<pre>
<strong>输入：</strong>s = "babgbag", t = "bag"
<code><strong>输出</strong></code><strong>：</strong><code>5
</code><strong>解释：</strong>
如下所示, 有 5 种可以从 s 中得到 <code>"bag" 的方案</code>。 
<code><strong><u>ba</u></strong>b<u><strong>g</strong></u>bag</code>
<code><strong><u>ba</u></strong>bgba<strong><u>g</u></strong></code>
<code><u><strong>b</strong></u>abgb<strong><u>ag</u></strong></code>
<code>ba<u><strong>b</strong></u>gb<u><strong>ag</strong></u></code>
<code>babg<strong><u>bag</u></strong></code>
</pre>
 
<p>&nbsp;</p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 &lt;= s.length, t.length &lt;= 1000</code></li>
	<li><code>s</code> 和 <code>t</code> 由英文字母组成</li>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/distinct-subsequences/submissions/) | [题解](https://leetcode.cn/problems/distinct-subsequences/solution/)

Solutions & Notes

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