Create 2-keys-keyboard.cpp

Author: kamyu104

C++/2-keys-keyboard.cpp

@@ -0,0 +1,18 @@
+// Time:  O(sqrt(n))
+// Space: O(1)
+
+class Solution {
+public:
+    int minSteps(int n) {
+        auto result = 0;
+        // the answer is the sum of prime factors
+        for (auto p = 2 ; p * p <= n; ++p) {
+            while (n % p == 0) {
+                result += p;
+                n /= p;
+            }
+        }
+        result += (n > 1) ? n : 0;
+        return result;
+    }
+};