Is String a rotation - Java Algorithm

Java examples for Algorithm:String

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Description

Is String a rotation

Demo Code

public class Main {
  public static void main(String args[]){
    String s_1 = "waterbottle";
    String s_2 = "erbottlewat"; // Yes they are rotations
    /*from   w  w w.j  a v a  2  s  .  c om*/
    String s_3 = "differentiate";
    String s_4 = "rent"; // They are just substrings
    
    String s_5 = "hello";
    String s_6 = "world"; // They are not substrings, and they are not rotations
    
    String s_7 = "computer";
    String s_8 = "computer"; // They are identical
    
    System.out.println("Method isRotation");
    System.out.println("s_1 is: " + s_1 + " and s_2 is: " + s_2);
    System.out.println("isRotation? " + isRotation(s_1, s_2));
    System.out.println();
    System.out.println("s_3 is: " + s_3 + " and s_4 is: " + s_4);
    System.out.println("isRotation? " + isRotation(s_3, s_4));
    System.out.println();
    System.out.println("s_5 is: " + s_5 + " and s_6 is: " + s_6);
    System.out.println("isRotation? " + isRotation(s_5, s_6));
    System.out.println();
    System.out.println("s_7 is: " + s_7 + " and s_8 is: " + s_8);
    System.out.println("isRotation? " + isRotation(s_7, s_8));
  }
  
  public static boolean isSubstring(String s1, String s2){ // given
    if(s1.contains(s2)) return true;
    return false;
  }
  
  public static boolean isRotation(String s1, String s2) {
    if(isSubstring(s1, s2) && isSubstring(s2, s1)) return false; // They are identical, and they are not rotations 
    
    if(s1.length() != s2.length()) return false; // They are definitely not rotations
    
    String newStr = s1+s1;
    
    if(isSubstring(newStr, s2)) return true;
    
    return false;
  }
}

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