leetcode80. Remove Duplicates from Sorted Array II

80. 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.

解法一

相同元素的个数依次累加。注意从1开始。

public class Solution {    public int removeDuplicates(int[] nums) {        if(nums.length == 0 && nums == null) {            return 0;        }        int i = 1, j = 1;        int count = 1;        while (j < nums.length) {            if (nums[j] != nums[j - 1]) {                count = 1;                nums[i++] = nums[j];            } else {                if (count < 2) {                    nums[i++] = nums[j];                    count++;                }            }            j++;        }        return i;    }}

解法二

判断i-2元素是否小于该元素，小于就把该元素添加到数组里。

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