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 (e.g., "waterbottle" is a rotation of "erbottlewat").

CareerCup1.8.cpp

#include <iostream>
#include <string>

bool IsSubString(std::string, std::string);
bool IsRotation(std::string, std::string);
int main()
{
  using namespace std;
	string str1,str2;
	cin>>str1>>str2;
	cout<<(IsRotation(str1,str2)?"Is Rotation":"Is not Rotation")<<endl;
	return 0;
}

bool IsSubString(std::string str1, std::string str2)
{
	if(str1.find(str2)<str1.size())
	{
		return true;
	}
	else
	{
		return false;
	}
}

bool IsRotation(std::string str1, std::string str2)
{
	if(str1.size()!=str2.size())
	{
		return false;
	}
	if(str1==str2)
	{
		return true;
	}
	return IsSubString(str2.substr(1,str2.size())+str2.substr(0,str2.size()-1),str1);
}