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53 lines
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53 lines
2.3 KiB
HTML
<p>You are given a <strong>0-indexed</strong> permutation of <code>n</code> integers <code>nums</code>.</p>
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<p>A permutation is called <strong>semi-ordered</strong> if the first number equals <code>1</code> and the last number equals <code>n</code>. You can perform the below operation as many times as you want until you make <code>nums</code> a <strong>semi-ordered</strong> permutation:</p>
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<ul>
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<li>Pick two adjacent elements in <code>nums</code>, then swap them.</li>
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</ul>
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<p>Return <em>the minimum number of operations to make </em><code>nums</code><em> a <strong>semi-ordered permutation</strong></em>.</p>
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<p>A <strong>permutation</strong> is a sequence of integers from <code>1</code> to <code>n</code> of length <code>n</code> containing each number exactly once.</p>
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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 = [2,1,4,3]
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> We can make the permutation semi-ordered using these sequence of operations:
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1 - swap i = 0 and j = 1. The permutation becomes [1,2,4,3].
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2 - swap i = 2 and j = 3. The permutation becomes [1,2,3,4].
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It can be proved that there is no sequence of less than two operations that make nums a semi-ordered permutation.
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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 = [2,4,1,3]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> We can make the permutation semi-ordered using these sequence of operations:
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1 - swap i = 1 and j = 2. The permutation becomes [2,1,4,3].
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2 - swap i = 0 and j = 1. The permutation becomes [1,2,4,3].
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3 - swap i = 2 and j = 3. The permutation becomes [1,2,3,4].
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It can be proved that there is no sequence of less than three operations that make nums a semi-ordered permutation.
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [1,3,4,2,5]
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> The permutation is already a semi-ordered permutation.
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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 <= nums.length == n <= 50</code></li>
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<li><code>1 <= nums[i] <= 50</code></li>
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<li><code>nums is a permutation.</code></li>
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</ul>
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