说明：  算法总体思想 对这k个子问题分别求解。如果子问题的规模仍然不够小，则再划分为k个子问题，如此递归的进行下去，直到问题规模足够小，很容易求出其解为止。
(The general idea of algorithm The K sub problem is solved separately. If the size of the sub problem is still not enough Small, then divided into k sub problems, so recursive go straight It is easy to find the solution until the scale of the problem is small enough.)