leetcode: Remove Duplicates from Sorted Array II [基本功]

Remove Duplicates from Sorted Array II

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.

tag： tow pointers

public class Solution {
    public int removeDuplicates(int[] nums) {
        if(nums == null || nums.length == 0) {
            return 0;
        }
        if(nums.length == 1) {
            return 1;
        }
        //初始化
        int count = 1;
        int pre = nums[1];
        
        for(int i = 2; i < nums.length; i++) {
            if(nums[i] != nums[i - 2]) {
                nums[count++] = pre;
                pre = nums[i];
            }
        }
        //处理最后一步
        nums[count++] = pre;
        return count;
    }
}