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| 1 | +<h2><a href="https://leetcode.com/problems/make-array-elements-equal-to-zero">3616. Make Array Elements Equal to Zero</a></h2><h3>Easy</h3><hr><p>You are given an integer array <code>nums</code>.</p> |
| 2 | + |
| 3 | +<p>Start by selecting a starting position <code>curr</code> such that <code>nums[curr] == 0</code>, and choose a movement <strong>direction</strong> of either left or right.</p> |
| 4 | + |
| 5 | +<p>After that, you repeat the following process:</p> |
| 6 | + |
| 7 | +<ul> |
| 8 | + <li>If <code>curr</code> is out of the range <code>[0, n - 1]</code>, this process ends.</li> |
| 9 | + <li>If <code>nums[curr] == 0</code>, move in the current direction by <strong>incrementing</strong> <code>curr</code> if you are moving right, or <strong>decrementing</strong> <code>curr</code> if you are moving left.</li> |
| 10 | + <li>Else if <code>nums[curr] > 0</code>: |
| 11 | + <ul> |
| 12 | + <li>Decrement <code>nums[curr]</code> by 1.</li> |
| 13 | + <li><strong>Reverse</strong> your movement direction (left becomes right and vice versa).</li> |
| 14 | + <li>Take a step in your new direction.</li> |
| 15 | + </ul> |
| 16 | + </li> |
| 17 | +</ul> |
| 18 | + |
| 19 | +<p>A selection of the initial position <code>curr</code> and movement direction is considered <strong>valid</strong> if every element in <code>nums</code> becomes 0 by the end of the process.</p> |
| 20 | + |
| 21 | +<p>Return the number of possible <strong>valid</strong> selections.</p> |
| 22 | + |
| 23 | +<p> </p> |
| 24 | +<p><strong class="example">Example 1:</strong></p> |
| 25 | + |
| 26 | +<div class="example-block"> |
| 27 | +<p><strong>Input:</strong> <span class="example-io">nums = [1,0,2,0,3]</span></p> |
| 28 | + |
| 29 | +<p><strong>Output:</strong> <span class="example-io">2</span></p> |
| 30 | + |
| 31 | +<p><strong>Explanation:</strong></p> |
| 32 | + |
| 33 | +<p>The only possible valid selections are the following:</p> |
| 34 | + |
| 35 | +<ul> |
| 36 | + <li>Choose <code>curr = 3</code>, and a movement direction to the left. |
| 37 | + |
| 38 | + <ul> |
| 39 | + <li><code>[1,0,2,<strong><u>0</u></strong>,3] -> [1,0,<strong><u>2</u></strong>,0,3] -> [1,0,1,<strong><u>0</u></strong>,3] -> [1,0,1,0,<strong><u>3</u></strong>] -> [1,0,1,<strong><u>0</u></strong>,2] -> [1,0,<strong><u>1</u></strong>,0,2] -> [1,0,0,<strong><u>0</u></strong>,2] -> [1,0,0,0,<strong><u>2</u></strong>] -> [1,0,0,<strong><u>0</u></strong>,1] -> [1,0,<strong><u>0</u></strong>,0,1] -> [1,<strong><u>0</u></strong>,0,0,1] -> [<strong><u>1</u></strong>,0,0,0,1] -> [0,<strong><u>0</u></strong>,0,0,1] -> [0,0,<strong><u>0</u></strong>,0,1] -> [0,0,0,<strong><u>0</u></strong>,1] -> [0,0,0,0,<strong><u>1</u></strong>] -> [0,0,0,0,0]</code>.</li> |
| 40 | + </ul> |
| 41 | + </li> |
| 42 | + <li>Choose <code>curr = 3</code>, and a movement direction to the right. |
| 43 | + <ul> |
| 44 | + <li><code>[1,0,2,<strong><u>0</u></strong>,3] -> [1,0,2,0,<strong><u>3</u></strong>] -> [1,0,2,<strong><u>0</u></strong>,2] -> [1,0,<strong><u>2</u></strong>,0,2] -> [1,0,1,<strong><u>0</u></strong>,2] -> [1,0,1,0,<strong><u>2</u></strong>] -> [1,0,1,<strong><u>0</u></strong>,1] -> [1,0,<strong><u>1</u></strong>,0,1] -> [1,0,0,<strong><u>0</u></strong>,1] -> [1,0,0,0,<strong><u>1</u></strong>] -> [1,0,0,<strong><u>0</u></strong>,0] -> [1,0,<strong><u>0</u></strong>,0,0] -> [1,<strong><u>0</u></strong>,0,0,0] -> [<strong><u>1</u></strong>,0,0,0,0] -> [0,0,0,0,0].</code></li> |
| 45 | + </ul> |
| 46 | + </li> |
| 47 | +</ul> |
| 48 | +</div> |
| 49 | + |
| 50 | +<p><strong class="example">Example 2:</strong></p> |
| 51 | + |
| 52 | +<div class="example-block"> |
| 53 | +<p><strong>Input:</strong> <span class="example-io">nums = [2,3,4,0,4,1,0]</span></p> |
| 54 | + |
| 55 | +<p><strong>Output:</strong> <span class="example-io">0</span></p> |
| 56 | + |
| 57 | +<p><strong>Explanation:</strong></p> |
| 58 | + |
| 59 | +<p>There are no possible valid selections.</p> |
| 60 | +</div> |
| 61 | + |
| 62 | +<p> </p> |
| 63 | +<p><strong>Constraints:</strong></p> |
| 64 | + |
| 65 | +<ul> |
| 66 | + <li><code>1 <= nums.length <= 100</code></li> |
| 67 | + <li><code>0 <= nums[i] <= 100</code></li> |
| 68 | + <li>There is at least one element <code>i</code> where <code>nums[i] == 0</code>.</li> |
| 69 | +</ul> |
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