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51 lines
2.5 KiB
HTML
51 lines
2.5 KiB
HTML
<p>An ant is on a boundary. It sometimes goes <strong>left</strong> and sometimes <strong>right</strong>.</p>
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<p>You are given an array of <strong>non-zero</strong> integers <code>nums</code>. The ant starts reading <code>nums</code> from the first element of it to its end. At each step, it moves according to the value of the current element:</p>
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<ul>
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<li>If <code>nums[i] < 0</code>, it moves <strong>left</strong> by<!-- notionvc: 55fee232-4fc9-445f-952a-f1b979415864 --> <code>-nums[i]</code> units.</li>
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<li>If <code>nums[i] > 0</code>, it moves <strong>right</strong> by <code>nums[i]</code> units.</li>
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</ul>
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<p>Return <em>the number of times the ant <strong>returns</strong> to the boundary.</em></p>
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<p><strong>Notes:</strong></p>
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<ul>
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<li>There is an infinite space on both sides of the boundary.</li>
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<li>We check whether the ant is on the boundary only after it has moved <code>|nums[i]|</code> units. In other words, if the ant crosses the boundary during its movement, it does not count.<!-- notionvc: 5ff95338-8634-4d02-a085-1e83c0be6fcd --></li>
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</ul>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [2,3,-5]
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<strong>Output:</strong> 1
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<strong>Explanation:</strong> After the first step, the ant is 2 steps to the right of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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After the second step, the ant is 5 steps to the right of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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After the third step, the ant is on the boundary.
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So the answer is 1.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [3,2,-3,-4]
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> After the first step, the ant is 3 steps to the right of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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After the second step, the ant is 5 steps to the right of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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After the third step, the ant is 2 steps to the right of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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After the fourth step, the ant is 2 steps to the left of the boundary<!-- notionvc: 61ace51c-559f-4bc6-800f-0a0db2540433 -->.
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The ant never returned to the boundary, so the answer is 0.
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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>1 <= nums.length <= 100</code></li>
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<li><code>-10 <= nums[i] <= 10</code></li>
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<li><code>nums[i] != 0</code></li>
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</ul>
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