求N个字符的不重复排列数，不是标准的递归写法，供求职时笔试参考。-Seek N-character array of non-repetition number, not an ordinary recursive formulation for the job when the written reference.

外螺旋矩阵的递归和非递归C编程方法 笔试中经常出现的题-Spiral Matrix outside the recursive and non recursive methods written in C programming problems often appear in