27. Remove Element

Question
Given an array and a value, remove all instances of that value in-place 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.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

• first attempt

class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int length=0;
        int change = -1;
        for(int i = 0;i<nums.size();i++)
        {
            if(nums[i]==val)
            {
                if(change == -1)
                    change = i;
            }
            else
            {
                length++;
                if(change == -1)
                    continue;
                if(change!=-1 &&change < i)
                {
                    int temp = nums[change];
                    nums[change] = nums[i];
                    nums[i]= temp;
                    do{
                        change++;
                    }while(change<=i&&nums[change]!=val);
                }
            }
        }
        return length;
        
    }
};