<p>Given an integer <code>k</code>, <em>return the minimum number of Fibonacci numbers whose sum is equal to </em><code>k</code>. The same Fibonacci number can be used multiple times.</p> <p>The Fibonacci numbers are defined as:</p> <ul> <li><code>F<sub>1</sub> = 1</code></li> <li><code>F<sub>2</sub> = 1</code></li> <li><code>F<sub>n</sub> = F<sub>n-1</sub> + F<sub>n-2</sub></code> for <code>n > 2.</code></li> </ul> It is guaranteed that for the given constraints we can always find such Fibonacci numbers that sum up to <code>k</code>. <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> k = 7 <strong>Output:</strong> 2 <strong>Explanation:</strong> The Fibonacci numbers are: 1, 1, 2, 3, 5, 8, 13, ... For k = 7 we can use 2 + 5 = 7.</pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> k = 10 <strong>Output:</strong> 2 <strong>Explanation:</strong> For k = 10 we can use 2 + 8 = 10. </pre> <p><strong class="example">Example 3:</strong></p> <pre> <strong>Input:</strong> k = 19 <strong>Output:</strong> 3 <strong>Explanation:</strong> For k = 19 we can use 1 + 5 + 13 = 19. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= k <= 10<sup>9</sup></code></li> </ul>