991.py

'''
On a broken calculator that has a number showing on its display, we can perform two operations:

Double: Multiply the number on the display by 2, or;
Decrement: Subtract 1 from the number on the display.
Initially, the calculator is displaying the number X.

Return the minimum number of operations needed to display the number Y.

 

Example 1:

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

class Solution(object):
    def brokenCalc(self, X, Y):
        """
        :type X: int
        :type Y: int
        :rtype: int
        """
        if X == Y:
            return 0
        if X > Y:
            return X-Y
        if(Y%2 == 1):
            return 1 + self.brokenCalc(X, Y+1)
        else:
            return 1 + self.brokenCalc(X, Y/2)