题目：

题解：

int removeDuplicates(int* nums, int numsSize) {
    if (numsSize <= 2) {
        return numsSize;
    }
    int slow = 2, fast = 2;
    while (fast < numsSize) {
        if (nums[slow - 2] != nums[fast]) {
            nums[slow] = nums[fast];
            ++slow;
        }
        ++fast;
    }
    return slow;
}