Mars Exploration HackerRank Solution

 Task

A space explorer’s ship crashed on Mars! They send a series of SOS messages to Earth for help.

Letters in some of the SOS messages are altered by cosmic radiation during transmission. Given the signal received by Earth as a string, s, determine how many letters of the SOS message have been changed by radiation.

Example

s = ‘SOSTOT’

The original message was SOSSOS. Two of the message’s characters were changed in transit.

Function Description

Complete the marsExploration function in the editor below.

marsExploration has the following parameter(s):

string s: the string as received on Earth

Returns

int: the number of letters changed during transmission

Input Format

There is one line of input: a single string, s.

Constraints

1 <= length of s <= 99

length of s modulo 3 = 0

s will contain only uppercase English letters, ascii[A-Z].

Sample Input 0

SOSSPSSQSSOR

Sample Output 0

3

Explanation 0

s = SOSSPSSQSSOR, and signal length |s| = 12. They sent 4 SOS messages (i.e.: 12/3 = 4).

Expected signal: SOSSOSSOSSOS

Recieved signal: SOSSPSSQSSOR

Difference:          X  X   X

Sample Input 1

SOSSOT

Sample Output 1

1

Explanation 1

s = SOSSOT, and signal length |s| = 6. They sent 2 SOS messages (i.e.: 6/3 = 2).

Expected Signal: SOSSOS     

Received Signal: SOSSOT

Difference:           X

Sample Input 2

SOSSOSSOS

Sample Output 2

0

Explanation 2

Since no character is altered, return 0.

Solution – Mars Exploration – HackerRank Solution

import java.io.*;

import java.math.*;

import java.security.*;

import java.text.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.regex.*;

class Result {

    /*

     * Complete the 'marsExploration' function below.

     *

     * The function is expected to return an INTEGER.

     * The function accepts STRING s as parameter.

     */

    public static int marsExploration(String s) {

    // Write your code here

int ans=0;

char [] str= s.toCharArray();

  for( int i = 0; i < str.length; i += 3 ){

        if( str[i] != 'S' ) ans++;

        if( str[i+1] != 'O' ) ans++;

        if( str[i+2] != 'S' ) ans++;

    }

    return ans;

    }

}

public class Solution {

    public static void main(String[] args) throws IOException {

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        String s = bufferedReader.readLine();

        int result = Result.marsExploration(s);

        bufferedWriter.write(String.valueOf(result));

        bufferedWriter.newLine();

        bufferedReader.close();

        bufferedWriter.close();

    }

}