80. Remove Duplicates from Sorted Array II

Description

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

For example,
Given sorted array nums = [1,1,1,2,2,3],

Your function should return length = 5, with the first five elements of nums being 1, 1, 2, 2 and 3. It doesn't matter what you leave beyond the new length.

Solution

Two-pointers

非常简洁的写法。

class Solution {
    public int removeDuplicates(int[] nums) {
        if (nums == null || nums.length < 1) {
            return 0;
        }
        
        int i = 0;
        for (int n : nums) {
            if (i < 2 || n > nums[i - 2]) { // elegant
                nums[i++] = n;
            }
        }
        
        return i;
    }
}