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1558. Minimum Numbers of Function Calls to Make Target Array 👍

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  int minOperations(vector<int>& nums) {
    const int maxNum = ranges::max(nums);
    return accumulate(nums.begin(), nums.end(), 0,
                      [](int subtotal, unsigned num) {
      return subtotal + popcount(num);
    }) + (maxNum == 0 ? 0 : (int)log2(maxNum));
  }
};

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class Solution {
  public int minOperations(int[] nums) {
    final int maxNum = Arrays.stream(nums).max().getAsInt();
    return Arrays.stream(nums).map(num -> Integer.bitCount(num)).sum() +
        (maxNum == 0 ? 0 : (int) (Math.log(maxNum) / Math.log(2)));
  }
}

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class Solution:
  def minOperations(self, nums: List[int]) -> int:
    maxNum = max(nums)
    return sum(num.bit_count() for num in nums) + \
        (0 if maxNum == 0 else maxNum.bit_length() - 1)