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49 lines
2.0 KiB
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<p>Given a single positive integer <code>x</code>, we will write an expression of the form <code>x (op1) x (op2) x (op3) x ...</code> where each operator <code>op1</code>, <code>op2</code>, etc. is either addition, subtraction, multiplication, or division (<code>+</code>, <code>-</code>, <code>*</code>, or <code>/)</code>. For example, with <code>x = 3</code>, we might write <code>3 * 3 / 3 + 3 - 3</code> which is a value of <font face="monospace">3</font>.</p>
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<p>When writing such an expression, we adhere to the following conventions:</p>
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<ul>
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<li>The division operator (<code>/</code>) returns rational numbers.</li>
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<li>There are no parentheses placed anywhere.</li>
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<li>We use the usual order of operations: multiplication and division happen before addition and subtraction.</li>
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<li>It is not allowed to use the unary negation operator (<code>-</code>). For example, "<code>x - x</code>" is a valid expression as it only uses subtraction, but "<code>-x + x</code>" is not because it uses negation.</li>
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</ul>
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<p>We would like to write an expression with the least number of operators such that the expression equals the given <code>target</code>. Return the least number of operators used.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> x = 3, target = 19
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<strong>Output:</strong> 5
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<strong>Explanation:</strong> 3 * 3 + 3 * 3 + 3 / 3.
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The expression contains 5 operations.
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> x = 5, target = 501
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<strong>Output:</strong> 8
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<strong>Explanation:</strong> 5 * 5 * 5 * 5 - 5 * 5 * 5 + 5 / 5.
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The expression contains 8 operations.
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> x = 100, target = 100000000
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> 100 * 100 * 100 * 100.
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The expression contains 3 operations.
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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>2 <= x <= 100</code></li>
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<li><code>1 <= target <= 2 * 10<sup>8</sup></code></li>
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</ul>
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