说明：  分支定界法（branch and bound）是一种求解整数规划问题的最常用算法。这种方法不但可以求解纯整数规划，还可以求解混合整数规划问题。分支定界法是一种搜索与迭代的方法，选择不同的分支变量和子问题进行分支。
(Branch and bound (branch and bound) is one of the most commonly used algorithms for integer programming problems. This method can not only solve pure integer programming, but also solve mixed integer programming problems. Branch and bound is a search and iterative method, which selects different branch variables and sub problems to branch.)