README.md

1558. Minimum Numbers of Function Calls to Make Target Array

Your task is to form an integer array nums from an initial array of zeros arr that is the same size as nums.

Return the minimum number of function calls to make nums from arr.

The answer is guaranteed to fit in a 32-bit signed integer.

Example 1:

Input: nums = [1,5]
Output: 5
Explanation: Increment by 1 (second element): [0, 0] to get [0, 1] (1 operation).
Double all the elements: [0, 1] -> [0, 2] -> [0, 4] (2 operations).
Increment by 1 (both elements)  [0, 4] -> [1, 4] -> [1, 5] (2 operations).
Total of operations: 1 + 2 + 2 = 5.

Example 2:

Input: nums = [2,2]
Output: 3
Explanation: Increment by 1 (both elements) [0, 0] -> [0, 1] -> [1, 1] (2 operations).
Double all the elements: [1, 1] -> [2, 2] (1 operation).
Total of operations: 2 + 1 = 3.

Example 3:

Input: nums = [4,2,5]
Output: 6
Explanation: (initial)[0,0,0] -> [1,0,0] -> [1,0,1] -> [2,0,2] -> [2,1,2] -> [4,2,4] -> [4,2,5](nums).

Example 4:

Input: nums = [3,2,2,4]
Output: 7

Example 5:

Input: nums = [2,4,8,16]
Output: 8

Constraints:

• 1 <= nums.length <= 10^5
• 0 <= nums[i] <= 10^9

Solutions (Rust)

1. Greedy

impl Solution {
    pub fn min_operations(nums: Vec<i32>) -> i32 {
        let mut nums = nums;
        let mut op0 = 0;
        let mut op1 = 0;

        for mut num in nums {
            let mut tmp = 0;

            while num > 0 {
                op0 += num % 2;
                tmp += 1;
                num /= 2;
            }
            op1 = op1.max(tmp - 1);
        }

        op0 + op1
    }
}