2571. Minimum Operations to Reduce an Integer to 0

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You are given a positive integer n, you can do the following operation any number of times:

  • Add or subtract a power of 2 from n.

Return the minimum number of operations to make n equal to 0.

A number x is power of 2 if x == 2i where i >= 0.

 

Example 1:

Input: n = 39
Output: 3
Explanation: We can do the following operations:
- Add 20 = 1 to n, so now n = 40.
- Subtract 23 = 8 from n, so now n = 32.
- Subtract 25 = 32 from n, so now n = 0.
It can be shown that 3 is the minimum number of operations we need to make n equal to 0.

Example 2:

Input: n = 54
Output: 3
Explanation: We can do the following operations:
- Add 21 = 2 to n, so now n = 56.
- Add 23 = 8 to n, so now n = 64.
- Subtract 26 = 64 from n, so now n = 0.
So the minimum number of operations is 3.

 

Constraints:

  • 1 <= n <= 105

Hints

Hint 1
Can we set/unset the bits in binary representation?
Hint 2
If there are multiple adjacent ones, how can we optimally add and subtract in 2 operations such that all ones get unset?
Hint 3
Bonus: Try to solve the problem with higher constraints: n ≤ 10^18.

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