Why my code is giving wrong answer on SPOJ? - c++

Question

Problem: http://www.spoj.com/problems/TSORT/
Below code is giving correct output on my computer but it is giving wrong answer on spoj. I have tried this with several inputs and it is giving correct output. But still showing wrong answer on spoj.
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
int t;
cin>>t;
cin.tie(0);
ios::sync_with_stdio(false);
int *arr= new int[t];
for(int i=0;i<t;i++)
{
cin>>arr[i];
}
sort(arr,arr+t);
for(int i=0;i<t;i++)
{
cout<<"\n";
cout<<arr[i];
}
return 0;
}

Answer 1

As Tejas says, using cin and cout is not recommended in problems of optimization, as they are slower in comparison to scanf and printf. Extending his answer, you need to note that you use the STL sort that is slower than STL qsort. having this in mind, I tried your code with qsort and i got AC:
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
using namespace std;
int a[1000008];
int compare (const void * a, const void * b)
{
return ( *(int*)a - *(int*)b );
}
int main()
{
int n,i;
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%d",&a[i]);
}
qsort(a,n,sizeof(int),compare);
for(i=0;i<n;i++)
printf("%d\n",a[i]);
return 0;
}
The int function compare is needed for the usage of qsort.
More info:
http://www.cplusplus.com/reference/cstdlib/qsort/
http://www.cplusplus.com/reference/algorithm/sort/

Answer 2

If you use cout<<arr[i]<<endl; it will give TLE instead of WA. So it means it has something to do with new line.
However if you want to get your answer accepted, you have to use printf and scanf instead of cin, cout. It is always suggested in such contests to use scanf and printf for reading large inputs.
I tried the following code and it was accepted
#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
int a[1000008];
int main()
{
int n,i;
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%d",&a[i]);
}
sort(a,a+n);
for(i=0;i<n;i++)
printf("%d\n",a[i]);
return 0;
}