Returns the square of distance between two input points
static int sqDist ( List < int > p1 , List < int > p2 ) { return ( p1 [ 0 ] - p2 [ 0 ] ) * ( p1 [ 0 ] - p2 [ 0 ] ) + ( p1 [ 1 ] - p2 [ 1 ] ) * ( p1 [ 1 ] - p2 [ 1 ] ) ; }