Project Notes

Basic Calculator II

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Description

tab: English
 
<p>Given a string <code>s</code> which represents an expression, <em>evaluate this expression and return its value</em>.&nbsp;</p>
 
<p>The integer division should truncate toward zero.</p>
 
<p>You may assume that the given expression is always valid. All intermediate results will be in the range of <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>.</p>
 
<p><strong>Note:</strong> You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as <code>eval()</code>.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> s = "3+2*2"
<strong>Output:</strong> 7
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> s = " 3/2 "
<strong>Output:</strong> 1
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> s = " 3+5 / 2 "
<strong>Output:</strong> 5
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
	<li><code>s</code> consists of integers and operators <code>(&#39;+&#39;, &#39;-&#39;, &#39;*&#39;, &#39;/&#39;)</code> separated by some number of spaces.</li>
	<li><code>s</code> represents <strong>a valid expression</strong>.</li>
	<li>All the integers in the expression are non-negative integers in the range <code>[0, 2<sup>31</sup> - 1]</code>.</li>
	<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit integer</strong>.</li>
</ul>
 
 
 
---
 
[submissions](https://leetcode.com/problems/basic-calculator-ii/submissions/) | [solutions](https://leetcode.com/problems/basic-calculator-ii/solutions/)
 
 
tab: 中文
 
<p>给你一个字符串表达式 <code>s</code> ，请你实现一个基本计算器来计算并返回它的值。</p>
 
<p>整数除法仅保留整数部分。</p>
 
<p>你可以假设给定的表达式总是有效的。所有中间结果将在&nbsp;<code>[-2<sup>31</sup>, 2<sup>31</sup>&nbsp;- 1]</code> 的范围内。</p>
 
<p><strong>注意：</strong>不允许使用任何将字符串作为数学表达式计算的内置函数，比如 <code>eval()</code> 。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例 1：</strong></p>
 
<pre>
<strong>输入：</strong>s = "3+2*2"
<strong>输出：</strong>7
</pre>
 
<p><strong>示例 2：</strong></p>
 
<pre>
<strong>输入：</strong>s = " 3/2 "
<strong>输出：</strong>1
</pre>
 
<p><strong>示例 3：</strong></p>
 
<pre>
<strong>输入：</strong>s = " 3+5 / 2 "
<strong>输出：</strong>5
</pre>
 
<p>&nbsp;</p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
	<li><code>s</code> 由整数和算符 <code>('+', '-', '*', '/')</code> 组成，中间由一些空格隔开</li>
	<li><code>s</code> 表示一个 <strong>有效表达式</strong></li>
	<li>表达式中的所有整数都是非负整数，且在范围 <code>[0, 2<sup>31</sup> - 1]</code> 内</li>
	<li>题目数据保证答案是一个 <strong>32-bit 整数</strong></li>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/basic-calculator-ii/submissions/) | [题解](https://leetcode.cn/problems/basic-calculator-ii/solution/)

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