说明：  给定n个矩阵构成的一个链<A1,A2,…,An>其中i=1，2，…，n，矩阵Ai的维数为pi-1pi,对乘积A1A2…An以一种最小化标量乘法次数的方式进行加全部括号。该问题应用动态规划算法
(N matrix of a given composition of a chain <A1,A2,…,An> Which i = 1,2, ..., n, the dimension of the matrix Ai is pi-1pi, on the product A1A2 ... An order to minimize a scalar multiplication method increases the number of all brackets. The problem by using dynamic programming algorithm)