Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 5

Description

Minimum Operations to Make the Integer Zero

You are given two integers num1 and num2.

In one operation, you can choose integer i in the range [0, 60] and subtract 2i + num2 from num1.

Return the integer denoting the minimum number of operations needed to make num1 equal to 0.

If it is impossible to make num1 equal to 0, return -1.

Example 1:

Input: num1 = 3, num2 = -2
Output: 3
Explanation: We can make 3 equal to 0 with the following operations:
- We choose i = 2 and subtract 22 + (-2) from 3, 3 - (4 + (-2)) = 1.
- We choose i = 2 and subtract 22 + (-2) from 1, 1 - (4 + (-2)) = -1.
- We choose i = 0 and subtract 20 + (-2) from -1, (-1) - (1 + (-2)) = 0.
It can be proven, that 3 is the minimum number of operations that we need to perform.

Example 2:

Input: num1 = 5, num2 = 7
Output: -1
Explanation: It can be proven, that it is impossible to make 5 equal to 0 with the given operation.

Constraints:

• 1 <= num1 <= 109
• -109 <= num2 <= 109

Solution

class Solution {
public:
  int makeTheIntegerZero(int num1, int num2) {
    if(!num2) return popcount(bit_cast<uint32_t>(num1));
    long long x = num1;
    for(int exp = 1; exp < 35; ++exp) {
      x -= num2;
      if(x < exp) return -1;
      if(x >= 0 && exp >= popcount(bit_cast<uint64_t>(x))) return exp;
    }
    return -1;
  }
};

// Accepted
// 542/542 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 11.02 % of cpp submissions (8.3 MB)