text: Computing the x ^ 2 + y ^ 2 for each given points and sorting them .
code: void preprocess ( int p [ ] , int x [ ] , int y [ ] , int n ) { for ( int i = 0 ; i < n ; i ++ ) p [ i ] = x [ i ] * x [ i ] + y [ i ] * y [ i ] ; sort ( p , p + n ) ; }