使用vector 模拟二维数组的复习，举例：



可以定义vector 的元素仍然是一个vector 比如， vector <vector <int> > 即表示一个二维int 数组，里层的vector <int> 表示第一维， 外层的vector 表示第二维：-Vector to simulate a two-dimensional array of review, for example: you can define the vector elements is still a vector such as, vector <vector <int> >　Means that a two-dimensional array of int, the inner layer of the vector <int> For the first dimension, the outer layer of the vector represents the second dimension: