Amazon interview question - To find the first repeated character in a String

Question: How to find the first repeated character in a String?

The below java program has been written in easy way to make the beginners understand how easy the way of coding is and how easily a concept can be achieved through programming.

import java.util.Scanner;

public class StrRepeat {

public static void main(String args[]){

//Get the string to check the non repreated character

System.out.println("Enter the String: ");

Scanner s = new Scanner(System.in);

String str = s.nextLine();

char fin = checkLetter(str);

System.out.println("The character is: " + fin);

s.close();

}

//To check each individual char for non repeated

private static char checkLetter(String str) {

// TODO Auto-generated method stub

//To split the string to character

char[] ary = str.toCharArray();

char val = 0;

//To get the length of character

int len = ary.length;

char temp[] = new char[len];

for (int i=0; i<len; i++){

for (int j=0; j<len; j++){

if (j!= i){

if(ary[i] == ary[j]){

temp[i] = '$';

}

}

}

}

for (int k = 0; k< len; k++){

if (temp[k] == '$' ){

val = ary[k];

break;

}

}

return val;

}

}

Output:

Enter the String: lmadam

The character is: m

Amazon interview question - Find first non repeated character in a string

Question: how to find the first non-repeated character in a String?

The below Java program has been optimised and written easy for understanding.

import java.util.Scanner;

public class StrRepeat {

           public static void main(String args[]){

          //Get the string to check the non repreated character

          System.out.println("Enter the String: ");

          Scanner s = new Scanner(System.in);

          String str = s.nextLine();

          char fin = checkLetter(str);

          System.out.println("The character is: " + fin);

          s.close();

}

//To check each individual char for non repeated

private static char checkLetter(String str) {

// TODO Auto-generated method stub

           //To split the string to character

           char[] ary = str.toCharArray(); 

           char val = 0;

           //To get the length of character

           int len = ary.length;

           char temp[] = new char[len];

           for (int i=0; i<len; i++){

                 for (int j=0; j<len; j++){

                    if (j!= i){

                         if(ary[i] == ary[j]){

                                   temp[i] = '$';

                         }

                   }

            }

}

for (int k = 0; k< len; k++){

if (temp[k] != '$' ){

val = ary[k];

break;

}

}

return val;

}

}

Output:

Enter the String: madam

The character is: d

Simple Java program for Palindrome

This program is simplified for easy understanding using the StringBuilder with reverse function in java.

import java.util.Scanner;

public class Palindrome {

public static void main(String args[]){

//Get the string to check 

System.out.println("Enter the string: ");

Scanner sc = new Scanner(System.in);

String inp = sc.nextLine();

sc.close();

//String to string builder to store in heap

StringBuilder sb = new StringBuilder();

sb.append(inp);

//Reverse function over the string 

sb = sb.reverse();

String temp = sb.toString();

//compare to check Palindrome

if (inp.equals(temp)){

System.out.println("The given string is a Palindrome.");

}else{

System.out.println("The given string is not a Palindrome.");

}

}

}

Output:

Enter the string: madam

The given string is a Palindrome.

Enter the string: Rajesh

The given string is not a Palindrome.