1 class Solution { 2 public: 3     int removeDuplicates(int A[], int n) { 4         if (n < 2) return n; 5         int rec = A[0], index = 1; 6         for (int i = 1; i < n; i++) { 7             if (A[i] != rec) { 8                 A[index++] = A[i]; 9                 rec = A[i];10             }11         }12         return index;13     }14 };