(LeetCode) 26. Remove Duplicates from Sorted Array

Remove Duplicates from Sorted Array

• Explore : Interview > Top Interveiw Questions > Easy Collection
• 분류 : Array
• 난이도 : Easy

Problem

Given a sorted array nums, remove the duplicates in-place such that each element appears only once and returns 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

Input: nums = [1,1,2]
Output: 2, nums = [1,2]
Explanation: 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.

Example 2

Input: nums = [0,0,1,1,1,2,2,3,3,4]
Output: 5, nums = [0,1,2,3,4]
Explanation: Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 respectively. It doesn't matter what values are set beyond the returned length.

Constraints

• 0 <= nums.length <= 3 * 104
• -10^{4} <= nums[i] <= 10^4
• nums is sorted in ascending order.

Solution

Exapnder

class Solution {
    fun removeDuplicates(nums: IntArray): Int {
        if (nums.isEmpty()) {
            return 0
        }
        var index = 0
        var result = 1

        for (i in 1 until nums.size) {
            if (nums[i] != nums[index]) {
                index++
                nums[index] = nums[i]
                result++
            }
        }
        return result
    }
}

Point of Thinking

• nums.length에 0이 포함되는 점
• O(1) 시간 복잡도를 요구하는 점
  • 단 한 번의 순회로 결과를 얻어내야 하는 방식
  • reduce()등의 중복 제거 메서드를 사용해서는 안 될 것