一辆汽车加满油后可以行驶N千米。旅途中有若干个加油站。若要使沿途的加油次数最少，设计一个有效的算法，指出应在那些加油站停靠加油。并证明你的算法能产生一个最优解。-You can fill up a car after driving N kilometers. There are several gas stations journey. To make the minimum number of refueling along the way to design an efficient algorithm, pointed at those stations should stop refueling. Algorithm and prove that you can produce an optimal solution.