here is a problem that I like to share with you ( the author of this problem is grand master havaliza ) .It is not hard but I like it's idea so I decide to share with you .

problem : In this problem you should help a thief to get rid of the police. in a city there are n intersections that some of them are connected with street, streets can have different length , each police car in this city have a speed equal 1 meter per second. the thief after stealing from bank realize that there are k police car in some intersection and they want to catch him ( the thief know their initial place ). h of these n intersections are connected to superhighway(when the thief reach there he can easily escape from the police car , the thief want to determine the minimum speed for his car to escape from the police ( the speed of the car is a positive integer and can not exceed than 2^k) note : if at a moment the thief and a police be in a same intersection or in a same point of one street the thief will be arrested . make a algorithm o(k*(n^2)) which determine the minimum speed or say that the escape is impossible?