Add C++ solution of problem #3191

Author: Cuda-Chen

3191/solution.cpp

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    int minOperations(vector<int>& A) {
+        int n = A.size();
+        int i = 0;
+        int ans = 0;
+        for(; i + 3 <= n; i++) {
+            if(A[i])
+                continue;
+
+            for(int j = i; j < i + 3; j++)
+                A[j] ^= 1;
+            ans++;
+        }
+
+        for(; i < n; i++) {
+            if(!A[i])
+                return -1;
+        }
+        return ans;
+    }
+};