[12 Feb 2020] A Program to check if strings are rotations of each other or not

A Program to check if strings are rotations of each other or not

Given a string s1 and a string s2, write a snippet to say whether s2 is a rotation of s1?
(eg given s1 = ABCD and s2 = CDAB, return true, given s1 = ABCD, and s2 = ACBD , return false)

Algorithm: areRotations(str1, str2)

    1. Create a temp string and store concatenation of str1 to
       str1 in temp.
                          temp = str1.str1
    2. If str2 is a substring of temp then str1 and str2 are 
       rotations of each other.

    Example:                 
                     str1 = "ABACD"
                     str2 = "CDABA"

     temp = str1.str1 = "ABACDABACD"
     Since str2 is a substring of temp, str1 and str2 are 
     rotations of each other.

// C++ program to check if two given strings

// are rotations of  each other

# include <bits/stdc++.h>

using namespace std;

  

/* Function checks if passed strings (str1

   and str2) are rotations of each other */

bool areRotations(string str1, string str2)

{

   /* Check if sizes of two strings are same */

   if (str1.length() != str2.length())

        return false;

  

   string temp = str1 + str1; 

  return (temp.find(str2) != string::npos);

}

  

/* Driver program to test areRotations */

int main()

{

   string str1 = "AACD", str2 = "ACDA";

   if (areRotations(str1, str2))

     printf("Strings are rotations of each other");

   else

      printf("Strings are not rotations of each other");

   return 0;

}

// Java program to check if two given strings are rotations of 

// each other

  

class StringRotation

{

    /* Function checks if passed strings (str1 and str2)

       are rotations of each other */

    static boolean areRotations(String str1, String str2)

    {

        // There lengths must be same and str2 must be 

        // a substring of str1 concatenated with str1.  

        return (str1.length() == str2.length()) &&

               ((str1 + str1).indexOf(str2) != -1);

    }

      

    // Driver method

    public static void main (String[] args)

    {

        String str1 = "AACD";

        String str2 = "ACDA";

  

        if (areRotations(str1, str2))

            System.out.println("Strings are rotations of each other");

        else

            System.out.printf("Strings are not rotations of each other");

    }

}

# Python program to check if strings are rotations of

# each other or not

  

# Function checks if passed strings (str1 and str2)

# are rotations of each other

def areRotations(string1, string2):

    size1 = len(string1)

    size2 = len(string2)

    temp = ''

  

    # Check if sizes of two strings are same

    if size1 != size2:

        return 0

  

    # Create a temp string with value str1.str1

    temp = string1 + string1

  

    # Now check if str2 is a substring of temp

    # string.count returns the number of occurrences of

    # the second string in temp

    if (temp.count(string2)> 0):

        return 1

    else:

        return 0

  

# Driver program to test the above function

string1 = "AACD"

string2 = "ACDA"

  

if areRotations(string1, string2):

    print "Strings are rotations of each other"

else:

    print "Strings are not rotations of each other"