有个M*N的矩阵，用26个字母按这个顺序填充。
ABCDEFGH
TUVWXYZI
SFEDCBAJ
RQPONMLK
就是从外往里转，其中M和N的值由键盘输入。
根据输入的M和N值不同，矩阵有不同的样子。

#include <stdio.h>
#include <stdlib.h>

int M, N;
void fun(char *p, int m, int n, int c)
{
    int i;
    for (i = 0; i < n; i ++)
    {
        p[i] = 'A' + (c++)%26;
    }
    for (i = 1; i < m; i ++)
    {
        p[i*N+n-1] = 'A' + (c++)%26;
    }
    for (i = n-2; i > 0; i --)
    {
        if (m == 1) break;
        p[(m-1)*N+i] = 'A' + (c++)%26;
    }
    for (i = m-1; i > 0; i --)
    {
        if (n == 1) break;
        p[i*N] = 'A' + (c++)%26;
    }
    m -= 2;
    if (m<=0) return;
    n -= 2;
    if (n<=0) return;
    p = p + N+1;
    fun(p, m, n, c);
}
int main(void)
{                                                                                                                 
    int i, j;                                                                                                     
    char *p;                                                                                                      
                                                                                                                  
    scanf("%d%d", &M, &N);                                                                                       
    p =  (char *)malloc(M*N*sizeof(char));                                                                        
                                                                                                                  
    fun(p, M, N, 0);                                                                                             
    for (i = 0; i < M; i ++)                                                                                      
    {                                                                                                            
        for (j = 0; j < N; j ++)                                                                                 
        {                                                                                                         
            printf("%c", *(p+N*i+j));                                                                             
        }                                                                                                         
        printf("\n");                                                                                             
    }                                                                                                            
    free(p);                                                                                                      
}              
办法是比较土，但能出结果。。。囧，楼主再测一测吧，看看有没有没有照顾到的情况