Add C++ solutions for leetcode 991.

Author: yanglr

cpp-leetcode/leetcode991-broken-calculator_direct_method.cpp

@@ -0,0 +1,44 @@
+#include<vector>
+#include<algorithm>
+#include<iostream>
+using namespace std;
+
+class Solution {
+public:
+    int brokenCalc(int startValue, int target) {
+        if (startValue > target) return startValue - target;
+
+        int count = 0;
+        while (startValue < target)
+        {
+            if (target % 2 == 0)
+            {
+                target /= 2;
+                count++;
+            }
+            else {
+                target += 1;
+                count++;
+            }
+        }
+        while (startValue > target)
+        {
+            target += 1;
+            count++;
+            if (startValue == target) return count;
+        }           
+        return count;
+    }
+};
+
+// Test
+int main()
+{
+    Solution sol;
+    int startValue = 3;
+    int target = 10;
+    auto res = sol.brokenCalc(startValue, target);
+    cout << res << endl;
+
+    return 0;
+}

cpp-leetcode/leetcode991-broken-calculator_optimize2.cpp

@@ -0,0 +1,32 @@
+#include<vector>
+#include<algorithm>
+#include<iostream>
+using namespace std;
+
+class Solution {
+public:
+    int brokenCalc(int startValue, int target) {
+        if (startValue > target) return startValue - target;
+        int count = 0;
+        while (target > startValue)
+        {
+            count++;
+            if (target % 2 == 1)
+                target++;
+            else target /= 2;
+        }
+        return count + (startValue - target); /* 一旦出现 startValue >= target 的情形, 方法1代码中的第二个while循环就不需要了 */
+    }
+};
+
+// Test
+int main()
+{
+    Solution sol;
+    int startValue = 3;
+    int target = 10;
+    auto res = sol.brokenCalc(startValue, target);
+    cout << res << endl;
+
+    return 0;
+}

cpp-leetcode/leetcode991-broken-calculator_optimize_remove_one_loop.cpp

@@ -0,0 +1,38 @@
+#include<vector>
+#include<algorithm>
+#include<iostream>
+using namespace std;
+
+class Solution {
+public:
+    int brokenCalc(int startValue, int target) {
+        if (startValue > target) return startValue - target;
+
+        int count = 0;
+        while (startValue < target)
+        {
+            if (target % 2 == 0)
+            {
+                target /= 2;
+                count++;
+            }
+            else {
+                target += 1;
+                count++;
+            }
+        }         
+        return count + (startValue - target); /* 一旦出现 startValue >= target 的情形, 方法1代码中的第二个while循环就不需要了 */
+    }
+};
+        
+// Test
+int main()
+{
+    Solution sol;
+    int startValue = 3;
+    int target = 10;
+    auto res = sol.brokenCalc(startValue, target);
+    cout << res << endl;
+
+    return 0;
+}