26. Remove duplicate from sorted array

https://leetcode.com/problems/remove-duplicates-from-sorted-array/

Given a sorted array nums, 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 by modifying the input array in-place with O(1) extra memory.

Example 1: 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 returned length.

  • code
class Solution {
    public int removeDuplicates(int[] nums) {
        int left = 1, right = 1;
        while (right < nums.length){
            if (nums[right] != nums[right - 1]){
                nums[left] = nums[right];
                left++;
            }
            right++;
        }
        return left;
    }
}
  • code
class Solution:
    def removeDuplicates(self, nums: List[int]) -> int:
        if not nums:
            return 0
        i = 0
        for v in nums:
            if v != nums[i]:
                i += 1
                nums[i] = v
        return i+1
  • code
def removeDuplicates2(self, nums: List[int]) -> int:
   left = 0
   if len(nums) == 0:
       return 0
   for i in range(len(nums)):
       if nums[i] != nums[left]:
           left+=1
           nums[left] = nums[i]
   return left + 1
  • code
var removeDuplicates = function(nums) {
    let index = 1;
    for (let i = 1; i < nums.length; i++){
        if (nums[i] != nums[i-1]) nums[index++] = nums[i];
    }
    return index;
};