1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution

Last updated: February 25, 2025

In this guide, you will get 1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution with the best time and space complexity. The solution to Minimum Number of Operations to Reinitialize a Permutation problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Table of Contents

  1. Problem Statement
  2. Complexity Analysis
  3. Minimum Number of Operations to Reinitialize a Permutation solution in C++
  4. Minimum Number of Operations to Reinitialize a Permutation solution in Java
  5. Minimum Number of Operations to Reinitialize a Permutation solution in Python
  6. Additional Resources
1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution image

Problem Statement of Minimum Number of Operations to Reinitialize a Permutation

You are given an even integer n​​​​​​. You initially have a permutation perm of size n​​ where perm[i] == i​ (0-indexed)​​​​.
In one operation, you will create a new array arr, and for each i:

If i % 2 == 0, then arr[i] = perm[i / 2].
If i % 2 == 1, then arr[i] = perm[n / 2 + (i – 1) / 2].

You will then assign arr​​​​ to perm.
Return the minimum non-zero number of operations you need to perform on perm to return the permutation to its initial value.

Example 1:

Input: n = 2
Output: 1
Explanation: perm = [0,1] initially.
After the 1st operation, perm = [0,1]
So it takes only 1 operation.

Example 2:

Input: n = 4
Output: 2
Explanation: perm = [0,1,2,3] initially.
After the 1st operation, perm = [0,2,1,3]
After the 2nd operation, perm = [0,1,2,3]
So it takes only 2 operations.

Example 3:

Input: n = 6
Output: 4

Constraints:

2 <= n <= 1000
n​​​​​​ is even.

Complexity Analysis

  • Time Complexity: O(n)
  • Space Complexity: O(1)

1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution in C++

class Solution {
 public:
  int reinitializePermutation(int n) {
    int ans = 0;
    int i = 1;

    do {
      if (i < n / 2)
        i = i * 2;
      else
        i = (i - n / 2) * 2 + 1;
      ++ans;
    } while (i != 1);

    return ans;
  }
};
/* code provided by PROGIEZ */

1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution in Java

class Solution {
  public int reinitializePermutation(int n) {
    int ans = 0;
    int i = 1;

    do {
      if (i < n / 2)
        i = i * 2;
      else
        i = (i - n / 2) * 2 + 1;
      ++ans;
    } while (i != 1);

    return ans;
  }
}
// code provided by PROGIEZ

1806. Minimum Number of Operations to Reinitialize a Permutation LeetCode Solution in Python

N/A
 # code by PROGIEZ

Additional Resources

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