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

March LeetCoding Challenge 23

Description

Broken Calculator

There is a broken calculator that has the integer startValue on its display initially. In one operation, you can:

• multiply the number on display by 2, or
• subtract 1 from the number on display.

Given two integers startValue and target, return the minimum number of operations needed to display target on the calculator.

Example 1:

Input: startValue = 2, target = 3
Output: 2
Explanation: Use double operation and then decrement operation {2 -> 4 -> 3}.

Example 2:

Input: startValue = 5, target = 8
Output: 2
Explanation: Use decrement and then double {5 -> 4 -> 8}.

Example 3:

Input: startValue = 3, target = 10
Output: 3
Explanation: Use double, decrement and double {3 -> 6 -> 5 -> 10}.

Constraints:

• 1 <= x, y <= 10^9

Solution

class Solution {
public:
  int brokenCalc(int X, int Y) {
    int answer = 0;
    while(Y > X) {
        if(Y & 1) Y += 1;
        else Y /= 2;
        answer += 1;
    }
    return answer + X - Y;
  }
};

// Accepted
// 84/84 cases passed (3 ms)
// Your runtime beats 32.55 % of cpp submissions
// Your memory usage beats 73.18 % of cpp submissions (5.8 MB)