|
| 1 | +--- |
| 2 | +id: semi-ordered-permutation |
| 3 | +title: Semi-Ordered Permutation |
| 4 | +sidebar_label: 2717-Semi_ordered-Permutation |
| 5 | +tags: |
| 6 | + - Array |
| 7 | + - Simulation |
| 8 | + |
| 9 | +description: "This is a solution to the 2717." |
| 10 | +--- |
| 11 | + |
| 12 | +## Problem Description |
| 13 | +You are given a 0-indexed permutation of `n` integers `nums`. |
| 14 | + |
| 15 | +A permutation is called semi-ordered if the first number equals `1` and the last number equals `n`. You can perform the below operation as many times as you want until you make `nums` a semi-ordered permutation: |
| 16 | + |
| 17 | +Pick two adjacent elements in `nums`, then swap them. |
| 18 | +Return the minimum number of operations to make `nums` a semi-ordered permutation. |
| 19 | + |
| 20 | +A permutation is a sequence of integers from `1` to `n` of length `n` containing each number exactly once. |
| 21 | + |
| 22 | + |
| 23 | +### Example |
| 24 | + |
| 25 | +**Example 1:** |
| 26 | + |
| 27 | + |
| 28 | +``` |
| 29 | +Input: nums = [2,1,4,3] |
| 30 | +Output: 2 |
| 31 | +Explanation: We can make the permutation semi-ordered using these sequence of operations: |
| 32 | +1 - swap i = 0 and j = 1. The permutation becomes [1,2,4,3]. |
| 33 | +2 - swap i = 2 and j = 3. The permutation becomes [1,2,3,4]. |
| 34 | +It can be proved that there is no sequence of less than two operations that make nums a semi-ordered permutation. |
| 35 | +``` |
| 36 | +**Example 2:** |
| 37 | +``` |
| 38 | +Input: nums = [2,4,1,3] |
| 39 | +Output: 3 |
| 40 | +Explanation: We can make the permutation semi-ordered using these sequence of operations: |
| 41 | +1 - swap i = 1 and j = 2. The permutation becomes [2,1,4,3]. |
| 42 | +2 - swap i = 0 and j = 1. The permutation becomes [1,2,4,3]. |
| 43 | +3 - swap i = 2 and j = 3. The permutation becomes [1,2,3,4]. |
| 44 | +It can be proved that there is no sequence of less than three operations that make nums a semi-ordered permutation. |
| 45 | +``` |
| 46 | +### Constraints |
| 47 | + |
| 48 | +- `2 <= nums.length == n <= 50` |
| 49 | + |
| 50 | +## Solution Approach |
| 51 | + |
| 52 | +### Intuition: |
| 53 | + |
| 54 | +To efficiently determine the Semi-Ordered Permutation |
| 55 | +## Solution Implementation |
| 56 | + |
| 57 | +### Code In Different Languages: |
| 58 | + |
| 59 | +<Tabs> |
| 60 | + <TabItem value="JavaScript" label="JavaScript" default> |
| 61 | + <SolutionAuthor name="@Ishitamukherjee2004"/> |
| 62 | + ```javascript |
| 63 | +class Solution { |
| 64 | + semiOrderedPermutation(nums) { |
| 65 | + let n = nums.length; |
| 66 | + let left = 0, right = n - 1; |
| 67 | + let operations = 0; |
| 68 | + while (left < right) { |
| 69 | + if (nums[left] === left + 1) { |
| 70 | + left++; |
| 71 | + } else if (nums[right] === n - right) { |
| 72 | + right--; |
| 73 | + } else { |
| 74 | + [nums[left], nums[right]] = [nums[right], nums[left]]; |
| 75 | + operations++; |
| 76 | + } |
| 77 | + } |
| 78 | + return operations; |
| 79 | + } |
| 80 | +} |
| 81 | + |
| 82 | + ``` |
| 83 | + |
| 84 | + </TabItem> |
| 85 | + <TabItem value="TypeScript" label="TypeScript"> |
| 86 | + <SolutionAuthor name="@Ishitamukherjee2004"/> |
| 87 | + ```typescript |
| 88 | + class Solution { |
| 89 | + semiOrderedPermutation(nums: number[]): number { |
| 90 | + let n = nums.length; |
| 91 | + let left = 0, right = n - 1; |
| 92 | + let operations = 0; |
| 93 | + while (left < right) { |
| 94 | + if (nums[left] === left + 1) { |
| 95 | + left++; |
| 96 | + } else if (nums[right] === n - right) { |
| 97 | + right--; |
| 98 | + } else { |
| 99 | + [nums[left], nums[right]] = [nums[right], nums[left]]; |
| 100 | + operations++; |
| 101 | + } |
| 102 | + } |
| 103 | + return operations; |
| 104 | + } |
| 105 | +} |
| 106 | +
|
| 107 | + ``` |
| 108 | + |
| 109 | + </TabItem> |
| 110 | + <TabItem value="Python" label="Python"> |
| 111 | + <SolutionAuthor name="@Ishitamukherjee2004"/> |
| 112 | + ```python |
| 113 | +class Solution: |
| 114 | + def semiOrderedPermutation(self, nums: List[int]) -> int: |
| 115 | + n = len(nums) |
| 116 | + left, right = 0, n - 1 |
| 117 | + operations = 0 |
| 118 | + while left < right: |
| 119 | + if nums[left] == left + 1: |
| 120 | + left += 1 |
| 121 | + elif nums[right] == n - right: |
| 122 | + right -= 1 |
| 123 | + else: |
| 124 | + nums[left], nums[right] = nums[right], nums[left] |
| 125 | + operations += 1 |
| 126 | + return operations |
| 127 | +
|
| 128 | + ``` |
| 129 | + |
| 130 | + </TabItem> |
| 131 | + <TabItem value="Java" label="Java"> |
| 132 | + <SolutionAuthor name="@Ishitamukherjee2004"/> |
| 133 | + ```java |
| 134 | + |
| 135 | +public class Solution { |
| 136 | + public int semiOrderedPermutation(int[] nums) { |
| 137 | + int n = nums.length; |
| 138 | + int left = 0, right = n - 1; |
| 139 | + int operations = 0; |
| 140 | + while (left < right) { |
| 141 | + if (nums[left] == left + 1) { |
| 142 | + left++; |
| 143 | + } else if (nums[right] == n - right) { |
| 144 | + right--; |
| 145 | + } else { |
| 146 | + int temp = nums[left]; |
| 147 | + nums[left] = nums[right]; |
| 148 | + nums[right] = temp; |
| 149 | + operations++; |
| 150 | + } |
| 151 | + } |
| 152 | + return operations; |
| 153 | + } |
| 154 | +} |
| 155 | +
|
| 156 | +
|
| 157 | + ``` |
| 158 | + |
| 159 | + </TabItem> |
| 160 | + <TabItem value="C++" label="C++"> |
| 161 | + <SolutionAuthor name="@Ishitamukherjee2004"/> |
| 162 | + ```cpp |
| 163 | + class Solution { |
| 164 | +public: |
| 165 | + int semiOrderedPermutation(vector<int>& nums) { |
| 166 | + int n = nums.size(); |
| 167 | + int left = 0, right = n - 1; |
| 168 | + int operations = 0; |
| 169 | + while (left < right) { |
| 170 | + if (nums[left] == left + 1) { |
| 171 | + left++; |
| 172 | + } else if (nums[right] == n - right) { |
| 173 | + right--; |
| 174 | + } else { |
| 175 | + swap(nums[left], nums[right]); |
| 176 | + operations++; |
| 177 | + } |
| 178 | + } |
| 179 | + |
| 180 | + return operations; |
| 181 | +} |
| 182 | +
|
| 183 | +}; |
| 184 | + ``` |
| 185 | +</TabItem> |
| 186 | +</Tabs> |
| 187 | + |
| 188 | +#### Complexity Analysis |
| 189 | + |
| 190 | +- Time Complexity: $$O(n)$$ |
| 191 | +- Space Complexity: $$O(1)$$ |
| 192 | +- The time complexity is $$O(n)$$ where n is the length of the input array nums. This is because the method iterates through the array once, performing a constant amount of work for each element. |
| 193 | +- The space complexity is $$O(1)$$ because we are not using any extra space. |
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