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30 lines
1.5 KiB
HTML
30 lines
1.5 KiB
HTML
<p>Given a string <code>s</code> which represents an expression, <em>evaluate this expression and return its value</em>. </p>
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<p>The integer division should truncate toward zero.</p>
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<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>
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<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>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre><strong>Input:</strong> s = "3+2*2"
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<strong>Output:</strong> 7
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</pre><p><strong class="example">Example 2:</strong></p>
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<pre><strong>Input:</strong> s = " 3/2 "
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<strong>Output:</strong> 1
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</pre><p><strong class="example">Example 3:</strong></p>
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<pre><strong>Input:</strong> s = " 3+5 / 2 "
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<strong>Output:</strong> 5
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= s.length <= 3 * 10<sup>5</sup></code></li>
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<li><code>s</code> consists of integers and operators <code>('+', '-', '*', '/')</code> separated by some number of spaces.</li>
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<li><code>s</code> represents <strong>a valid expression</strong>.</li>
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<li>All the integers in the expression are non-negative integers in the range <code>[0, 2<sup>31</sup> - 1]</code>.</li>
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<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit integer</strong>.</li>
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</ul>
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