深搜+剪枝，简单字符串。

1 #include 
     
       2 #include 
      
        3  4 #define MAXLEN 105 5 #define MAXNUM 105 6  7 char buf[MAXNUM][MAXLEN]; 8 char src1[MAXLEN], src2[MAXLEN]; 9 int case_n, n;10 11 int f(int index, int len) {12     int max = 0;13     int i=0, j, k;14     char *p;15 16     while (i+max < len) {17         for (j=0; j<=max; ++j)18             src1[j] = src2[max-j] = buf[index][i+j];19         src1[max+1] = src2[max+1] = '\0';20         k = 1;21         for (j=0; j