Skip to content
Related Articles

Related Articles

Improve Article
Save Article
Like Article

Minimum number of chairs required to ensure that every worker is seated at any instant

  • Last Updated : 22 Apr, 2021

Given a string S representing the record of workers entering and leaving the rest area, where E represents entering and L represents leaving the rest area. For each worker, one chair is required. The task is to find the minimum number of chairs required so that there is no shortage of chairs at any given time.

Examples:

Input: S = “EELEE”
Output: 3
Explanation:
Step 1: One person enters. Therefore, 1 chair is required for now.
Step 2: Another person enters. Therefore, the number of chairs are required to be increased to 2.
Step 3: One person leaves. Therefore, no need to increase the number of chairs.
Step 4: Another person enters. Still, no need to increase the number of chairs.
Step 4: Another person enters. Therefore, number of chairs are needed to be increased to 3.
Therefore, minimum 3 chairs are required such that there is never a shortage of chairs.

Input: S = “EL”
Output: 1

Approach: Follow the steps below to solve the problem:

  • Initialize a variable, say, count.
  • Iterate over the characters of the string using a variable, say i.
  • If the ith character is ‘E’, then increase the count by 1, as more chairs are required.
  • If the ith character is ‘L’, then decrease the count by 1 as one of the chairs is emptied.
  • Print the maximum value of count obtained at any step.

Below is the implementation of the above approach:

C++




// C++ implementation of
// the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the minimum number
// of chairs required to ensure that
// every worker is seated at any time
int findMinimumChairs(string s)
{
    // Stores the number of
    // chairs required
    int count = 0;
 
    // Pointer to iterate
    int i = 0;
 
    // Stores minimum number of
    // chairs required
    int mini = INT_MIN;
 
    // Iterate over every character
    while (i < s.length()) {
 
        // If character is 'E'
        if (s[i] == 'E')
 
            // Increase the count
            count++;
 
        // Otherwise
        else
            count--;
 
        // Update maximum value of count
        // obtained at any given time
        mini = max(count, mini);
 
        i++;
    }
 
    // Return mini
    return mini;
}
 
// Driver Code
int main()
{
    // Input
 
    // Given String
    string s = "EELEE";
 
    // Function call to find the
    // minimum number of chairs
    cout << findMinimumChairs(s);
}

Java




// Java program for the above approach
import java.io.*;
import java.util.*;
 
class GFG
{
   
  // Function to find the minimum number
  // of chairs required to ensure that
  // every worker is seated at any time
  static int findMinimumChairs(String s)
  {
     
    // Stores the number of
    // chairs required
    int count = 0;
 
    // Pointer to iterate
    int i = 0;
 
    // Stores minimum number of
    // chairs required
    int mini = Integer.MIN_VALUE;
 
    // Iterate over every character
    while (i < s.length()) {
 
      // If character is 'E'
      if (s.charAt(i) == 'E')
 
        // Increase the count
        count++;
 
      // Otherwise
      else
        count--;
 
      // Update maximum value of count
      // obtained at any given time
      mini = Math.max(count, mini);
 
      i++;
    }
 
    // Return mini
    return mini;
  }
 
  // Driver code
  public static void main(String[] args)
  {
    // Input
 
    // Given String
    String s = "EELEE";
 
    // Function call to find the
    // minimum number of chairs
    System.out.print(findMinimumChairs(s));
  }
}
 
// This code is contributed by code_hunt.

Python3




# Python 3 implementation of
# the above approach
import sys
 
# Function to find the minimum number
# of chairs required to ensure that
# every worker is seated at any time
def findMinimumChairs(s):
   
    # Stores the number of
    # chairs required
    count = 0
 
    # Pointer to iterate
    i = 0
 
    # Stores minimum number of
    # chairs required
    mini = -sys.maxsize - 1
 
    # Iterate over every character
    while (i < len(s)):
       
        # If character is 'E'
        if (s[i] == 'E'):
           
            # Increase the count
            count += 1
 
        # Otherwise
        else:
            count -= 1
 
        # Update maximum value of count
        # obtained at any given time
        mini = max(count, mini)
        i += 1
 
    # Return mini
    return mini
 
# Driver Code
if __name__ == '__main__':
   
    # Input
 
    # Given String
    s = "EELEE"
 
    # Function call to find the
    # minimum number of chairs
    print(findMinimumChairs(s))
     
    # This code is contributed by ipg2016107.

C#




// C# program to implement
// the above approach
using System;
using System.Collections.Generic;
 
class GFG
{
 
  // Function to find the minimum number
  // of chairs required to ensure that
  // every worker is seated at any time
  static int findMinimumChairs(string s)
  {
 
    // Stores the number of
    // chairs required
    int count = 0;
 
    // Pointer to iterate
    int i = 0;
 
    // Stores minimum number of
    // chairs required
    int mini = Int32.MinValue;
 
    // Iterate over every character
    while (i < s.Length) {
 
      // If character is 'E'
      if (s[i] == 'E')
 
        // Increase the count
        count++;
 
      // Otherwise
      else
        count--;
 
      // Update maximum value of count
      // obtained at any given time
      mini = Math.Max(count, mini);
 
      i++;
    }
 
    // Return mini
    return mini;
  }
 
 
  // Driver code
  public static void Main()
  {
    // Input
 
    // Given String
    string s = "EELEE";
 
    // Function call to find the
    // minimum number of chairs
    Console.WriteLine(findMinimumChairs(s));
  }
}
 
// This code is contributed by code_hunt.

Javascript




<script>
 
// Javascript implementation of
// the above approach
 
// Function to find the minimum number
// of chairs required to ensure that
// every worker is seated at any time
function findMinimumChairs(s)
{
    // Stores the number of
    // chairs required
    var count = 0;
 
    // Pointer to iterate
    var i = 0;
 
    // Stores minimum number of
    // chairs required
    var mini = -2147483647;
 
    // Iterate over every character
    while (i < s.length) {
 
        // If character is 'E'
        if (s[i] == 'E')
 
            // Increase the count
            count++;
 
        // Otherwise
        else
            count--;
 
        // Update maximum value of count
        // obtained at any given time
        mini = Math.max(count, mini);
 
        i++;
    }
 
    // Return mini
    return mini;
}
 
// Driver Code
    // Input
 
    // Given String
    var s = "EELEE";
 
    // Function call to find the
    // minimum number of chairs
    document.write(findMinimumChairs(s));
 
</script>

 
 

Output: 
3

 

 

Time Complexity: O(N)
Auxiliary Space: O(1)

 


My Personal Notes arrow_drop_up
Recommended Articles
Page :

Start Your Coding Journey Now!