Remove Duplicates from Sorted Array

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 by modifying the input array in-place with O(1) extra memory.

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.

Solution: Selection sort

Using insertion sort to move element to the left side, if element is a duplicate, ignore and move to the next element until the end.

Note: There's a small difference than selection sort. In selection sort we use an int pointing at the start of the second part. But in this problem, we need to compare the new element with the end of the sorted array. So we use an int pointing at the end of the sorted array.

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        if(nums.empty()) return 0;

        int index = 0;
        for(int i=0; i<nums.size(); i++) {
            if(nums[index] < nums[i]) {
                index += 1;
                swap(nums[index], nums[i]);
            }
        }
        return index+1;
    }
};

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