80 Remove Duplicates from Sorted Array II

80. Remove Duplicates from Sorted Array II

1. Question

Follow up for "Remove Duplicates": What if duplicates are allowed at mosttwice?

For example, Given sorted arraynums=[1,1,1,2,2,3],

Your function should return length =5, with the first five elements ofnumsbeing1,1,2,2and3. It doesn't matter what you leave beyond the new length.

2. Implementation

class Solution {
    public int removeDuplicates(int[] nums) {
        if (nums.length <= 2) {
            return nums.length;
        }

        int count = 1, index = 1;

        for (int i = 1; i < nums.length; i++) {
            if (nums[i - 1] != nums[i]) {
                count = 1;
                nums[index++] = nums[i];
            }
            else if (count < 2) {
                nums[index++] = nums[i];
                ++count;
            }
        }
        return index;
    }
}

3. Time & Space Complexity

时间复杂度O(n), 空间复杂度O(1)