26 Remove Duplicates from Sorted Array

26. Remove Duplicates from Sorted Array

1. Question

Given a sorted array, remove the duplicates in-place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this bymodifying the input array in-place with O(1) extra memory.

Example:

Given nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.
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 index = 1;
        for (int i = 1; i < nums.length; i++) {
            if (nums[i - 1] != nums[i]) {
                nums[index++] = nums[i];
            }
        }
        return index;
    }
}

3. Time & Space Complexity

时间复杂度O(n), 空间复杂度O(1)