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Removing elements between the two zeros

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  • Difficulty Level : Hard
  • Last Updated : 25 May, 2022
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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#




// 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: 

100

 

Time Complexity : O(N), where N is the size of input string.
 


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