Package g0201_0300.s0224_basic_calculator

Class Solution

java.lang.Object
g0201_0300.s0224_basic_calculator.Solution
public class Solution extends Object
224 - Basic Calculator.<p>Hard</p> <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><strong>Example 1:</strong></p> <p><strong>Input:</strong> s = &ldquo;1 + 1&rdquo;</p> <p><strong>Output:</strong> 2</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> s = &quot; 2-1 + 2 &quot;</p> <p><strong>Output:</strong> 3</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> s = &ldquo;(1+(4+5+2)-3)+(6+8)&rdquo;</p> <p><strong>Output:</strong> 23</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= s.length <= 3 * 10<sup>5</sup></code></li> <li><code>s</code> consists of digits, <code>'+'</code>, <code>'-'</code>, <code>'('</code>, <code>')'</code>, and <code>' '</code>.</li> <li><code>s</code> represents a valid expression.</li> <li><code>'+'</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>'-'</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>

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • calculate

      public int calculate(String s)