Merge two sorted arrays into res [ ]
int i = 0 , j = 0 , k = 0 ; while ( i < n && j < m ) { if ( a [ i ] <= b [ j ] ) { res [ k ] = a [ i ] ; i += 1 ; k += 1 ; } else { res [ k ] = b [ j ] ; j += 1 ; k += 1 ; } }