# HackerRank Mars Exploration problem solution

In this HackerRank Mars Exploration problem, you have Given the signal received by Earth as a string, determine how many letters of the SOS message have been changed by the radiation.

## Problem solution in Python programming.

```#!/bin/python3

import sys

S = input().strip()

num_errors = 0

for i, char in enumerate(S):
if i%3 == 1:
if char != 'O':
num_errors += 1
else:
if char != 'S':
num_errors += 1

print(num_errors)```

## Problem solution in Java Programming.

```import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String S = in.next();
int count =0;
for(int i=0;i<S.length();i =i+3){
if(S.charAt(i)!='S'){
count++;
}
if(S.charAt(i+1)!='O'){
count++;

}

if(S.charAt(i+2)!='S'){
count ++;
}

}

System.out.println(count);

}
}```

### Problem solution in C++ programming.

```#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

int main(){
ios::sync_with_stdio(false);
string str;
cin >> str;
int ans = 0;
for( int i = 0; i < str.size(); i += 3 ){
if( str[i] != 'S' ) ans++;
if( str[i+1] != 'O' ) ans++;
if( str[i+2] != 'S' ) ans++;
}
cout << ans << '\n';
return 0;
}```

### Problem solution in C programming.

```#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int main(){
char* S = (char *)malloc(10240 * sizeof(char));
scanf("%s",S);
int len = strlen(S);
int iTemp = 0;
int alt = 0;
for(iTemp=0;iTemp<len;iTemp=iTemp+3)
{
if(S[iTemp] != 'S')
{
alt++;
}
if(S[iTemp+1] != 'O')
{
alt++;
}
if(S[iTemp+2] != 'S')
{
alt++;
}
}
printf("%d\n",alt);
return 0;
}```

### Problem solution in JavaScript programming.

```process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
input_stdin += data;
});

process.stdin.on('end', function () {
input_stdin_array = input_stdin.split("\n");
main();
});

return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
var num=0;
var test;
for(var i=0,len=S.length;i<len;i++){
test=(i%3==1) ? 'O' : 'S';
if(S.charAt(i)!=test){
num++;
}
}
console.log(num);
}```