Return distance between the centers
function dis ( x1 , y1 , x2 , y2 ) { return Math . sqrt ( ( x1 - x2 ) * ( x1 - x2 ) + ( y1 - y2 ) * ( y1 - y2 ) ) ; } function check ( c1 , c2 , k ) { let min = 0 ; let max = 0 ;