# Removing elements between the two zeros

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"
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 ` `using` `namespace` `std; ` ` `  `// Function to find the string  ` `// after operation ` `string findstring(string s) ` `{ ` `    ``int` `n = s.length(); ` `         `  `    ``// Travesing 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` ` `  `    ``# Travesing 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 = ``""``; ` `         `  `        ``// Travesing 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) `

Output:

```100
```

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

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