[leetcode] Remove Duplicates from Sorted Array II

public class Solution {

    public int removeDuplicates(int[] A) {
        int n = A.length;
        if (n <= 2)
            return n;
        int index = 2;
        for (int i = 2; i < n; i++) {
            if (A[i] != A[index - 2])
                A[index++] = A[i];
        }
        return index;
    }

    public int removeDuplicates2(int[] A) {
        if (A.length <= 2)
            return A.length;

        int prev = 1; // point to previous
        int curr = 2; // point to current

        while (curr < A.length) {
            if (A[curr] == A[prev] && A[curr] == A[prev - 1]) {
                curr++;
            } else {
                prev++;
                A[prev] = A[curr];
                curr++;
            }
        }

        return prev + 1;
    }

    public static void main(String[] args) {
        System.out.println(new Solution().removeDuplicates(new int[] { 1, 1, 1, 2 }));
        System.out.println(new Solution().removeDuplicates(new int[] { 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5 }));
        System.out.println(new Solution().removeDuplicates(new int[] {}));
        System.out.println(new Solution().removeDuplicates(new int[] { 1 }));
        System.out.println(new Solution().removeDuplicates(new int[] { 1, 1 }));
    }

}