Create minimum-operations-to-make-a-special-number.cpp

Author: kamyu104

C++/minimum-operations-to-make-a-special-number.cpp

@@ -0,0 +1,21 @@
+// Time:  O(n)
+// Space; O(1)
+
+// math, greedy
+class Solution {
+public:
+    int minimumOperations(string num) {
+        static const string target1 = "05";
+        static const string target2 = "27";
+
+        vector<int> lookup(10);
+        for (int i = size(num) - 1; i >= 0; --i) {
+            if ((target1.find(num[i]) != string::npos && lookup[0]) ||
+                (target2.find(num[i]) != string::npos && lookup[5])) {
+                return (size(num) - i) - 2;
+            }
+            lookup[num[i] - '0'] = 1;
+        }
+        return size(num) - lookup[0];
+    }
+};