Remove Duplicates from Sorted Array

06/25/2016 Array Two Pointers


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 in place with constant memory.

For example, Given input array 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.


Result: Accepted Time: 0ms

Here should be some explanations.

int removeDuplicates(int* nums, int numsSize) {
    int *top = nums ,*ptr = nums,*last=nums;
    const int  limit = nums + numsSize;
    if(numsSize == 0)
        return 0;
    *(top++) = *(ptr++);
    while(ptr < limit)
        if(*last != *ptr)
            *(top++) = *(ptr);
    return top-nums;

Complexity Analytics

  • Time Complexity:
  • Space Complexity: