// 1.8 Assume you have a method isSubstring which checks if one word is a substring of another. Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 using only one call to isSubstring (i.e., “waterbottle” is a rotation of “erbottlewat”).

 #include <cstdio>

 #include <cstring>

 using namespace std;

 class Solution {

 public:

     bool isStringRotation(char *s1, char *s2) {

         if (s1 == nullptr || s2 == nullptr) {

             return false;

         }

         int len1, len2;

         len1 = strlen(s1);

         len2 = strlen(s2);

         if (len1 != len2) {

             return false;

         }

         const int MAXLEN = ;

         static char tmp[MAXLEN];

         tmp[] = ;

         strcat(tmp, s1);

         strcat(tmp, s1);

         return strstr(tmp, s2) != nullptr;

     }

 private:

     bool isSubstring(char *haystack, char *needle) {

         if (haystack == nullptr || needle == nullptr) {

             return false;

         }

         return strstr(haystack, needle) != nullptr;

     }

 };

 int main()

 {

     char s1[];

     char s2[];

     Solution sol;

     while (scanf("%s%s", s1, s2) == ) {

         printf("\"%s\" is ", s2);

         if (!sol.isStringRotation(s1, s2)) {

             printf("not ");

         }

         printf("a rotation of \"%s\".\n", s1);

     }

     return ;

 }