Cracking The Coding Interview 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”).
//
// 题意：先写一个判断是否为字串的函数，然后写一个是否是旋转串的函数，调用一次是否为字串函数，来判断是否为旋转串
// 下面的方法来自于http://hawstein.com/posts/ctci-solutions-contents.html
#include <iostream>
#include <string>
using namespace std;
bool isSubstring(string s1, string s2)
{
	if(s1.find(s2) != string::npos) return true;
	else return false;
}

bool isRotation(string s1, string s2)
{
	if(s1.length() != s2.length() || s1.length()<=0)
		return false;
	return isSubstring(s1+s1, s2);
}

int  main()
{
	string s1= "kfuc";
	string s2= "fuck";
	cout<<isRotation(s1,s2)<<endl;
	return 0;
}