80.Remove Duplicates from Sorted Array II

class Solution {
public:
    int removeDuplicates(int A[], int n) {
        if (n <= 2) return n;
        int pre = 0, cur = 1, count = 1;
        while (cur < n) {
            if (A[pre] == A[cur] && count == 0) ++cur;
            else {
                if (A[pre] == A[cur]) --count;
                else count = 1;
                A[++pre] = A[cur++];
            }
        }
        return pre + 1;
    }
};