New Problem Solution "Broken Calculator"

Author: haoel

README.md

@@ -11,6 +11,7 @@ LeetCode
 |1030|[Matrix Cells in Distance Order](https://leetcode.com/problems/matrix-cells-in-distance-order/) | [C++](./algorithms/cpp/matrixCellsInDistanceOrder/MatrixCellsInDistanceOrder.cpp)|Easy|
 |1029|[Two City Scheduling](https://leetcode.com/problems/two-city-scheduling/) | [C++](./algorithms/cpp/twoCityScheduling/TwoCityScheduling.cpp)|Easy|
 |993|[Cousins in Binary Tree](https://leetcode.com/problems/cousins-in-binary-tree/) | [C++](./algorithms/cpp/cousinsInBinaryTree/CousinsInBinaryTree.cpp)|Easy|
+|991|[Broken Calculator](https://leetcode.com/problems/broken-calculator/) | [C++](./algorithms/cpp/brokenCalculator/BrokenCalculator.cpp)|Medium|
 |990|[Satisfiability of Equality Equations](https://leetcode.com/problems/satisfiability-of-equality-equations/) | [C++](./algorithms/cpp/satisfiabilityOfEqualityEquations/SatisfiabilityOfEqualityEquations.cpp)|Medium|
 |989|[Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/) | [C++](./algorithms/cpp/addToArrayFormOfInteger/AddToArrayFormOfInteger.cpp)|Easy|
 |988|[Smallest String Starting From Leaf](https://leetcode.com/problems/smallest-string-starting-from-leaf/) | [C++](./algorithms/cpp/smallestStringStartingFromLeaf/SmallestStringStartingFromLeaf.cpp)|Medium|

algorithms/cpp/brokenCalculator/BrokenCalculator.cpp

@@ -0,0 +1,54 @@
+// Source : https://leetcode.com/problems/broken-calculator/
+// Author : Hao Chen
+// Date   : 2019-05-01
+
+/***************************************************************************************************** 
+ *
+ * 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}.
+ * 
+ * Example 2:
+ * 
+ * Input: X = 5, Y = 8
+ * Output: 2
+ * Explanation: Use decrement and then double {5 -> 4 -> 8}.
+ * 
+ * Example 3:
+ * 
+ * Input: X = 3, Y = 10
+ * Output: 3
+ * Explanation:  Use double, decrement and double {3 -> 6 -> 5 -> 10}.
+ * 
+ * Example 4:
+ * 
+ * Input: X = 1024, Y = 1
+ * Output: 1023
+ * Explanation: Use decrement operations 1023 times.
+ * 
+ * Note:
+ * 
+ * 	1 <= X <= 10^9
+ * 	1 <= Y <= 10^9
+ ******************************************************************************************************/
+
+
+class Solution {
+public:
+    int brokenCalc(int X, int Y) {
+        if (X >= Y) return X-Y ;
+        if ( Y%2 ==0 ) return brokenCalc(X, Y/2) + 1;
+        return brokenCalc(X, Y+1) + 1;
+    }
+};