约瑟夫问题 假设有n个小孩坐成一个环，假如从第一个小孩开始数，如果数到m个小孩，则该小孩离开，问最后留下的小孩是第几个小孩？ -The Josephus problem.Assuming n students sit in a ring.we start count from the first student.when we count m,the student who has the number of m musts leave.wo now ask the last one s