Project Notes

Basic Calculator

3 min read

Nav: << previous: 223.矩形面积 | next: 225.用队列实现栈 >>

Description

tab: English
 
<p>Given a string <code>s</code> representing a valid expression, implement a basic calculator to evaluate it, and return <em>the result of the evaluation</em>.</p>
 
<p><strong>Note:</strong> You are <strong>not</strong> 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 = &quot;1 + 1&quot;
<strong>Output:</strong> 2
</pre>
 
<p><strong class="example">Example 2:</strong></p>
 
<pre>
<strong>Input:</strong> s = &quot; 2-1 + 2 &quot;
<strong>Output:</strong> 3
</pre>
 
<p><strong class="example">Example 3:</strong></p>
 
<pre>
<strong>Input:</strong> s = &quot;(1+(4+5+2)-3)+(6+8)&quot;
<strong>Output:</strong> 23
</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 digits, <code>&#39;+&#39;</code>, <code>&#39;-&#39;</code>, <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, and <code>&#39; &#39;</code>.</li>
	<li><code>s</code> represents a valid expression.</li>
	<li><code>&#39;+&#39;</code> is <strong>not</strong> used as a unary operation (i.e., <code>&quot;+1&quot;</code> and <code>&quot;+(2 + 3)&quot;</code> is invalid).</li>
	<li><code>&#39;-&#39;</code> could be used as a unary operation (i.e., <code>&quot;-1&quot;</code> and <code>&quot;-(2 + 3)&quot;</code> is valid).</li>
	<li>There will be no two consecutive operators in the input.</li>
	<li>Every number and running calculation will fit in a signed 32-bit integer.</li>
</ul>
 
 
 
---
 
[submissions](https://leetcode.com/problems/basic-calculator/submissions/) | [solutions](https://leetcode.com/problems/basic-calculator/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>注意: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 = "1 + 1"
<strong>输出：</strong>2
</pre>
 
<p><strong>示例 2：</strong></p>
 
<pre>
<strong>输入：</strong>s = " 2-1 + 2 "
<strong>输出：</strong>3
</pre>
 
<p><strong>示例 3：</strong></p>
 
<pre>
<strong>输入：</strong>s = "(1+(4+5+2)-3)+(6+8)"
<strong>输出：</strong>23
</pre>
 
<p>&nbsp;</p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 &lt;= s.length &lt;= 3&nbsp;* 10<sup>5</sup></code></li>
	<li><code>s</code> 由数字、<code>'+'</code>、<code>'-'</code>、<code>'('</code>、<code>')'</code>、和 <code>' '</code> 组成</li>
	<li><code>s</code> 表示一个有效的表达式</li>
	<li><code>'+'</code>&nbsp;不能用作一元运算(例如， <code>"+1"</code>&nbsp;和 <code>"+(2 + 3)"</code>&nbsp;无效)</li>
	<li><code>'-'</code>&nbsp;可以用作一元运算(即 <code>"-1"</code>&nbsp;和 <code>"-(2 + 3)"</code>&nbsp;是有效的)</li>
	<li>输入中不存在两个连续的操作符</li>
	<li>每个数字和运行的计算将适合于一个有符号的 32位 整数</li>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/basic-calculator/submissions/) | [题解](https://leetcode.cn/problems/basic-calculator/solution/)

Solutions & Notes

properties:
  note.updated:
    displayName: Last Updated
  note.relative_links:
    displayName: Related Links
  note.desc:
    displayName: Description
  note.grade:
    displayName: Rating
  note.program_language:
    displayName: Language
  note.time_complexity:
    displayName: TC
  note.space_complexity:
    displayName: SC
views:
  - type: table
    name: Solutions & Notes
    filters:
      and:
        - file.hasLink(this.file)
        - file.tags.containsAny("leetcode/solution", "leetcode/note")
    order:
      - file.name
      - desc
      - program_language
      - time_complexity
      - space_complexity
      - grade
      - relative_links
      - updated
    sort:
      - property: grade
        direction: ASC
      - property: time_complexity
        direction: ASC
      - property: program_language
        direction: ASC
    columnSize:
      file.name: 104
      note.space_complexity: 65
      note.grade: 126

Similar Problems

properties:
  note.lcTopics:
    displayName: Topics
  note.lcAcRate:
    displayName: AC Rate
  note.favorites:
    displayName: Favorites
  note.grade:
    displayName: Rating
  note.translatedTitle:
    displayName: Title (CN)
  note.lcDifficulty:
    displayName: Difficulty
views:
  - type: table
    name: Similar Problems
    filters:
      and:
        - file.hasLink(this.file)
        - similarQuestions.contains(this.file)
    order:
      - file.name
      - translatedTitle
      - lcTopics
      - lcDifficulty
      - lcAcRate
      - grade
      - favorites
    sort:
      - property: file.name
        direction: ASC
      - property: lcTopics
        direction: DESC
    columnSize:
      note.translatedTitle: 240
      note.lcTopics: 347
      note.lcAcRate: 75
      note.grade: 122

Graph View

Backlinks