Runs fine in Atom but Runtime error(sigsegv) in codestudio compiler

The pattern to print if n=5 is

1 2 3 4 5

11 12 13 14 15

21 22 23 24 25

16 17 18 19 20

6 7 8 9 10

if anyone can tell me why and where is the overflow/segmentation fault.

     #include <bits/stdc++.h> 

     vector<string> printPattern(int n)
     {
     int matrix[n][n];
     int i=0;
     int j=n-1;
     int k=1;
     while(i<=j)
     {
           int x=0;
                    while (x <n&& i<=j) 
                    {
                         matrix[i][x]=k;
                     k++;
                     x++;
                    }
           i++;
           int y=0;
                   while(y<n && i<=j)
                   {   
                        matrix[j][y]=k;
                        k++;
                        y++;
                   }
           j--;
     }
     for (int i = 0; i <= n-1; i++)
     {
           for (int j = 0; j <=n-1; j++)
           {
                 cout<< matrix[i][j];
                 if (j < n - 1)
                 {
                       cout << " ";
                 }
           }
      cout<<endl;
     }
     }

Its a 2D array approach to a pattern problem in codingninja's codestudio interview problems.