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| 1 | +<h2><a href="https://leetcode.com/problems/jump-game-iv/">1345. Jump Game IV</a></h2><h3>Hard</h3><hr><div><p>Given an array of integers <code>arr</code>, you are initially positioned at the first index of the array.</p> |
| 2 | + |
| 3 | +<p>In one step you can jump from index <code>i</code> to index:</p> |
| 4 | + |
| 5 | +<ul> |
| 6 | + <li><code>i + 1</code> where: <code>i + 1 < arr.length</code>.</li> |
| 7 | + <li><code>i - 1</code> where: <code>i - 1 >= 0</code>.</li> |
| 8 | + <li><code>j</code> where: <code>arr[i] == arr[j]</code> and <code>i != j</code>.</li> |
| 9 | +</ul> |
| 10 | + |
| 11 | +<p>Return <em>the minimum number of steps</em> to reach the <strong>last index</strong> of the array.</p> |
| 12 | + |
| 13 | +<p>Notice that you can not jump outside of the array at any time.</p> |
| 14 | + |
| 15 | +<p> </p> |
| 16 | +<p><strong class="example">Example 1:</strong></p> |
| 17 | + |
| 18 | +<pre><strong>Input:</strong> arr = [100,-23,-23,404,100,23,23,23,3,404] |
| 19 | +<strong>Output:</strong> 3 |
| 20 | +<strong>Explanation:</strong> You need three jumps from index 0 --> 4 --> 3 --> 9. Note that index 9 is the last index of the array. |
| 21 | +</pre> |
| 22 | + |
| 23 | +<p><strong class="example">Example 2:</strong></p> |
| 24 | + |
| 25 | +<pre><strong>Input:</strong> arr = [7] |
| 26 | +<strong>Output:</strong> 0 |
| 27 | +<strong>Explanation:</strong> Start index is the last index. You do not need to jump. |
| 28 | +</pre> |
| 29 | + |
| 30 | +<p><strong class="example">Example 3:</strong></p> |
| 31 | + |
| 32 | +<pre><strong>Input:</strong> arr = [7,6,9,6,9,6,9,7] |
| 33 | +<strong>Output:</strong> 1 |
| 34 | +<strong>Explanation:</strong> You can jump directly from index 0 to index 7 which is last index of the array. |
| 35 | +</pre> |
| 36 | + |
| 37 | +<p> </p> |
| 38 | +<p><strong>Constraints:</strong></p> |
| 39 | + |
| 40 | +<ul> |
| 41 | + <li><code>1 <= arr.length <= 5 * 10<sup>4</sup></code></li> |
| 42 | + <li><code>-10<sup>8</sup> <= arr[i] <= 10<sup>8</sup></code></li> |
| 43 | +</ul> |
| 44 | +</div> |
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