Find the direction from given string

Given a string of containing only L’s and R’s which represents left rotation and right rotation respectively. The task is to find the final direction of pivot(i.e N/E/S/W). Let a pivot is pointed towards north(N) in a compass.

Examples:

Input: str = "LLRLRRL"
Output: W
In this input string we rotate pivot to left
when a L char is encountered and right when 
R is encountered. 

Input: str = "LL"
Output: S

Approach:



  1. Use a counter that incremented on seeing R and decremented on seeing L.
  2. Finally use modulo on counter to get the direction.
  3. If count is negative then directions will be different.Check the code for negative as well.

Below is the implementation of above approach:

C++

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// CPP implementation of above approach
#include<bits/stdc++.h>
using namespace std;
  
// Function to find the final direction
string findDirection(string s)
{
    int count = 0;
    string d = "";
  
    for (int i = 0; i < s.length(); i++) 
    {
  
        if (s[0] == '\n')
            return NULL;
  
        if (s[i] == 'L')
            count--;
        else 
        {
            if (s[i] == 'R')
                count++;
        }
    }
  
    // if count is positive that implies
    // resultant is clockwise direction
    if (count > 0) 
    {
  
        if (count % 4 == 0)
            d = "N";
        else if (count % 4 == 1)
            d = "E";
        else if (count % 4 == 2)
            d = "S";
        else if (count % 4 == 3)
            d = "W";
    }
  
    // if count is negative that implies
    // resultant is anti-clockwise direction
    if (count < 0) 
    {
  
        if (count % 4 == 0)
            d = "N";
        else if (count % 4 == -1)
            d = "W";
        else if (count % 4 == -2)
            d = "S";
        else if (count % 4 == -3)
            d = "E";
    }
    return d;
}
  
    // Driver code
    int main()
    {
        string s = "LLRLRRL";
        cout << (findDirection(s)) << endl;
  
        s = "LL";
        cout << (findDirection(s)) << endl;
    }
  
// This code is contributed by 
// SURENDRA_GANGWAR

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Java

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// Java implementation of above approach
import java.util.*;
  
class GFG {
  
    // Function to find the final direction
    static String findDirection(String s)
    {
        int count = 0;
        String d = "";
  
        for (int i = 0; i < s.length(); i++) {
  
            if (s.charAt(0) == '\n')
                return null;
  
            if (s.charAt(i) == 'L')
                count--;
            else {
                if (s.charAt(i) == 'R')
                    count++;
            }
        }
  
        // if count is positive that implies
        // resultant is clockwise direction
        if (count > 0) {
  
            if (count % 4 == 0)
                d = "N";
            else if (count % 4 == 1)
                d = "E";
            else if (count % 4 == 2)
                d = "S";
            else if (count % 4 == 3)
                d = "W";
        }
  
        // if count is negative that implies
        // resultant is anti-clockwise direction
        if (count < 0) {
  
            if (count % 4 == 0)
                d = "N";
            else if (count % 4 == -1)
                d = "W";
            else if (count % 4 == -2)
                d = "S";
            else if (count % 4 == -3)
                d = "E";
        }
        return d;
    }
  
    // Driver code
    public static void main(String[] args)
    {
        String s = "LLRLRRL";
        System.out.println(findDirection(s));
  
        s = "LL";
        System.out.println(findDirection(s));
    }
}

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C#

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// C# implementation of above approach
using System;
  
class GFG 
{
  
// Function to find the final direction
static String findDirection(String s)
{
    int count = 0;
    String d = "";
  
    for (int i = 0; i < s.Length; i++)
    {
  
        if (s[0] == '\n')
            return null;
  
        if (s[i] == 'L')
            count--;
        else {
            if (s[i] == 'R')
                count++;
        }
    }
  
    // if count is positive that implies
    // resultant is clockwise direction
    if (count > 0)
    {
  
        if (count % 4 == 0)
            d = "N";
        else if (count % 4 == 1)
            d = "E";
        else if (count % 4 == 2)
            d = "S";
        else if (count % 4 == 3)
            d = "W";
    }
  
    // if count is negative that implies
    // resultant is anti-clockwise direction
    if (count < 0)
    {
  
        if (count % 4 == 0)
            d = "N";
        else if (count % 4 == -1)
            d = "W";
        else if (count % 4 == -2)
            d = "S";
        else if (count % 4 == -3)
            d = "E";
    }
    return d;
}
  
// Driver code
public static void Main()
{
    String s = "LLRLRRL";
    Console.WriteLine(findDirection(s));
  
    s = "LL";
    Console.WriteLine(findDirection(s));
}
}
  
// This code is contributed by Shashank

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PHP

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<?php
// PHP implementation of above approach
  
// Function to find the final direction
function findDirection($s)
{
    $count = 0;
    $d = "";
  
    for ($i = 0; 
         $i < strlen($s); $i++)
    {
        if ($s[0] == '\n')
            return null;
  
        if ($s[$i] == 'L')
            $count -= 1;
        else
        {
            if ($s[$i] == 'R')
                $count += 1;
        }
    }
              
    // if count is positive that implies
    // resultant is clockwise direction
    if ($count > 0) 
    {
        if ($count % 4 == 0)
            $d = "N";
        else if ($count % 4 == 1)
            $d = "E";
        else if ($count % 4 == 2)
            $d = "S";
        else if ($count % 4 == 3)
            $d = "W";
    }
      
    // if count is negative that 
    // implies resultant is 
    // anti-clockwise direction
    if ($count < 0) 
    {
        if ($count % 4 == 0)
            $d = "N";
        else if ($count % 4 == -1)
            $d = "W";
        else if ($count % 4 == -2)
            $d = "S";
        else if ($count % 4 == -3)
            $d = "E";
    }
    return $d;
}
  
// Driver code
$s = "LLRLRRL";
echo findDirection($s)."\n";
  
$s = "LL";
echo findDirection($s)."\n";
  
// This code is contributed
// by ChitraNayal    
?>

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Output:

W
S


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