子集树回溯法 试设计一个用回溯法搜索子集空间树的函数。该函数的参数包括结点可行性判定函数和上界函数等必要的函数，并将此函数用于解装载问题。

装载问题描述如下：有一批共n个集装箱要装上艘载重量为c的轮船，其中集装箱i的重量为wi。找出一种最优装载方案，将轮船尽可能装满，即在装载体积不受限制的情况下，将尽可能重的集装箱装上轮船。-A subset of the trial design of a backtracking tree with backtracking search a subset of the space tree function. The function of the parameters include the node to determine the feasibility of function and the upper bound of the function and other necessary functions, and this function is used to load solution of the problem. Loading Problem described as follows: there is a group of n containers loaded onto ships to load ships for the c, in which the weight of the container i is wi. Find an optimal load programs, filled with ships as far as possible, that the volume loading unrestricted case, as far as possible re-loaded onto the container ship.