Removing elements between the two zeros

Last Updated : 07 Oct, 2022

Given an integer N which shows the size of the string and in the next line given a string which contains a string of character with only zero and one. The task is to remove a single character each time that comes in between the two zero characters.
During each turn, only one character from the string will be removed that satisfies the following condition :

It must be surrounded by zeroes on both sides.

Examples:

Input : str = "1001
Output : str = "1001"

Input : str = "10101
Output : str = "1001"

Use a loop from 1 to N - 1 and check if any element lies between two zeros such that s[i - 1] = '0' and s[i + 1] = '0'. If the condition is satisfied then, delete the character at that position, ad start searching for patterns again.

C++

// C++ program to delete elements between zeros
#include <bits/stdc++.h>
using namespace std;

// Function to find the string 
// after operation
string findstring(string s)
{
    int n = s.length();
        
    // Traversing through string 
    for (int i = 1; i < n - 1; i++)
    {
        // Checking for character 
        // Between two zeros
        if ((s.at(i - 1) == '0' && 
            s.at(i + 1) == '0'))
        {

            // deleting the character 
            // At specific position
            s.erase(i, 1);
            
            i--;
            if (i > 0 && s.at(i - 1) == '0')
                 i--;
                        
            // updating the length 
            // of the string
            n = s.length();
        }
    }
            
    return s;
}
    
// Drivers code
int main() {
    
    cout << findstring("100100");
    return 0;
}

Java

// Java program to delete elements between zeros
import java.util.*;

public class GFG 
{
    // Function to find the string 
    // after operation
    static String findstring(String s)
    {
        int n = s.length();
            
        // use for loop to remove the
        // character between two zeros
        for (int i = 1; i < n - 1; i++)
        { 
            // Checking for character 
            // Between two zeros
            if ((s.charAt(i - 1) == '0' && 
                 s.charAt(i + 1) == '0'))
            {
                    
                // deleting the character 
                // At specific position
                s = s.substring(0, i) + s.substring(i + 1);
                
                i--;
                if (i > 0 && s.charAt(i - 1) == '0')
                    i--;
                        
                // updating the length 
                // of the string
                n = s.length();
            }
        }
            
        return s;
    }
    
    // Driver code
    public static void main(String[] args)
    {
       String s="100100";
       System.out.println(findstring(s));
    }
}

Python3

# Python3 program to delete elements
# between zeros

# Function to find the string
# after operation
def findstring(s):
    
    n = len(s)
    s = list(s)
    i = 1

    # Traversing through string
    while i < n - 1:

        # Checking for character
        # Between two zeros
        if (s[i - 1] == '0' and 
            s[i + 1] == '0'):

            # Deleting the character
            # At specific position
            s.pop(i)

            i -= 1
            if i > 0 and s[i - 1] == '0':
                i -= 1

            # Updating the length
            # of the string
            n = len(s)
        i += 1

    return ''.join(s)

# Driver code
if __name__ == '__main__':

    print (findstring('100100'))

# This code is contributed by rutvik_56

// C# program to delete 
// elements between zeros
using System;

class GFG
{
    // Function to find the 
    // string after operation
    static string findstring(string s)
    {
        int n = s.Length;
        string st = "";
        
        // Traversing through string 
        for (int i = 1; i < n - 1; i++)
        {
            // Checking for character 
            // Between two zeros
            if ((s[i - 1] == '0' && 
                 s[i + 1] == '0'))
            {
    
                // deleting the character 
                // At specific position
                st = s.Remove(i, 1);
                s = st;
                
                i--;
                if (i > 0 && 
                    s[i - 1] == '0')
                    i--;
                            
                // updating the length 
                // of the string
                n = s.Length;
            }
        }                 
        return s;
    }
    
    // Driver code
    static void Main()
    {
        Console.Write(findstring("100100"));
    }
}

// This code is contributed by 
// Manish Shaw(manishshaw1)

JavaScript

<script>

// JavaScript program to delete elements
// between zeros

// Function to find the string
// after operation
function findstring(s){
    
    let n = s.length
    s = s.split('')
    let i = 1

    // Traversing through string
    while(i < n - 1){

        // Checking for character
        // Between two zeros
        if (s[i - 1] == '0' && s[i + 1] == '0'){

            // Deleting the character
            // At specific position
            s.splice(i,1);

            i -= 1
            if(i > 0 && s[i - 1] == '0')
                i -= 1

            // Updating the length
            // of the string
            n = s.length
        }
        i += 1
    }

    return s.join('')
}

// Driver code

document.write(findstring('100100'),"</br>")

// This code is contributed by shinjanpatra

</script>

Output:

Time Complexity: O(N²), where N is the size of the input string and using erase function to delete the value in the string.
Auxiliary Space: O(1)

Remove Leading Zeros From String in C++

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Removing elements between the two zeros

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