#define N 21
/*据此做出邻接矩阵，若第i个城市与第j个城市相邻，则metro[i][j]=1,否则metro[i][j]=0。
*/
int metro[N][N]={{0},/*邻接矩阵*/
{0,1,1,1,1,1,1},
{0,1,1,1,1},
{0,1,1,1,0,0,1},
{0,1,1,0,1,1},
{0,1,0,0,1,1,1,0,0,1,0,0,0,0,0,0,1},
{0,1,0,1,0,1,1,1,1,1},
{0,0,0,0,0,0,1,1,1},
{0,0,0,0,0,0,1,1,1,1,0,0,1},
{0,0,0,0,0,1,1,0,1,1,0,0,1,1,1,0,1},
{0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,1,0,0,0,1},
{0,0,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,1},
{0,0,0,0,0,0,0,0,1,1,0,1,1,1,0,0,0,0,0,1,1},
{0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1},
{0,0,0,0,0,0,0,0,0,1,0,0,0,1,1,1,1},
{0,0,0,0,0,0,0,0,0,0,1,0,0,1,1,1,1,1,0,1},
{0,0,0,0,1,0,0,0,1,0,0,0,0,1,1,1,1},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1},
{0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,1,0,0,1,1,1},
{0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1}};

不明白此邻接矩阵中的各个小序列。希望各位大哥、高手帮忙解释。
本人是新手！谢谢！

刚在C语言那边回答了你的问题，这是个21*21的矩阵的数组表示，缺少的项都是0。