mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-01-10 18:48:13 +08:00
49 lines
1.7 KiB
HTML
49 lines
1.7 KiB
HTML
<p>You are given an integer array <code>cards</code> of length <code>4</code>. You have four cards, each containing a number in the range <code>[1, 9]</code>. You should arrange the numbers on these cards in a mathematical expression using the operators <code>['+', '-', '*', '/']</code> and the parentheses <code>'('</code> and <code>')'</code> to get the value 24.</p>
|
|
|
|
<p>You are restricted with the following rules:</p>
|
|
|
|
<ul>
|
|
<li>The division operator <code>'/'</code> represents real division, not integer division.
|
|
|
|
<ul>
|
|
<li>For example, <code>4 / (1 - 2 / 3) = 4 / (1 / 3) = 12</code>.</li>
|
|
</ul>
|
|
</li>
|
|
<li>Every operation done is between two numbers. In particular, we cannot use <code>'-'</code> as a unary operator.
|
|
<ul>
|
|
<li>For example, if <code>cards = [1, 1, 1, 1]</code>, the expression <code>"-1 - 1 - 1 - 1"</code> is <strong>not allowed</strong>.</li>
|
|
</ul>
|
|
</li>
|
|
<li>You cannot concatenate numbers together
|
|
<ul>
|
|
<li>For example, if <code>cards = [1, 2, 1, 2]</code>, the expression <code>"12 + 12"</code> is not valid.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
|
|
<p>Return <code>true</code> if you can get such expression that evaluates to <code>24</code>, and <code>false</code> otherwise.</p>
|
|
|
|
<p> </p>
|
|
<p><strong class="example">Example 1:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> cards = [4,1,8,7]
|
|
<strong>Output:</strong> true
|
|
<strong>Explanation:</strong> (8-4) * (7-1) = 24
|
|
</pre>
|
|
|
|
<p><strong class="example">Example 2:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> cards = [1,2,1,2]
|
|
<strong>Output:</strong> false
|
|
</pre>
|
|
|
|
<p> </p>
|
|
<p><strong>Constraints:</strong></p>
|
|
|
|
<ul>
|
|
<li><code>cards.length == 4</code></li>
|
|
<li><code>1 <= cards[i] <= 9</code></li>
|
|
</ul>
|