Find unique numbers in array

Question

Well, I have to find how many different numbers are in an array.

For example if array is: 1 9 4 5 8 3 1 3 5

The output should be 6, because 1,9,4,5,8,3 are uniqu

Answer 1

Please dry run your code See in the outer for loop for each element it is counted more than one inside inner loop.let us say the loop contains 1,2,3,4.1.....elements dry run it in the second iteration and third iteration 1 is counted because 1 is 1!=2 as well as 1!=3

Now solution time!!

#include
#include
#include
#define ll long long
using namespace std;
ll arr[1000007]={0};
int main()
{
  ios_base::sync_with_stdio(false);//used for fast i/o
    ll n;cin>>n;
      for(ll i=1;i<=n;i++)
        cin>>arr[i];

        sort(arr,arr+n);

       ll cnt=0;
                for(ll i=1;i<=n-1;i++)
                  {
                   if(arr[i+1]-arr[i]==0)
                     cnt++;
                  }
                 cout<