991. Broken Calculator

Problem

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 <= startValue, target <= 10^9

Solution (Java)

class Solution {
    public int brokenCalc(int startValue, int target) {
        int result = 0;
        while (startValue != target) {
            if (target > startValue && target % 2 != 0) {
                target += 1;
                result++;
            } else if (target > startValue) {
                target /= 2;
                result++;
            } else {
                result += startValue - target;
                break;
            }
        }
        return result;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).