public class Solution {
    
    public int removeDuplicates(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        
        int size = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != nums[size]) {
                nums[++size] = nums[i];
            }
        }
        return size + 1;
    }
}