# Delete middle element of a stack

Given a stack with push(), pop(), empty() operations, delete middle of it without using any additional data structure.

```Input  : Stack[] = [1, 2, 3, 4, 5]
Output : Stack[] = [1, 2, 4, 5]

Input  : Stack[] = [1, 2, 3, 4, 5, 6]
Output : Stack[] = [1, 2, 4, 5, 6]
```

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

The idea is to use recursive calls. We first remove all items one by one, then we recur. After recursive calls, we push all items back except the middle item.

## C++

 `// C++ code to delete middle of a stack ` `// without using additional data structure. ` `#include ` `using` `namespace` `std; ` ` `  `// Deletes middle of stack of size ` `// n. Curr is current item number ` `void` `deleteMid(stack<``char``> &st, ``int` `n, ` `                          ``int` `curr=0) ` `{ ` `   ``// If stack is empty or all items ` `   ``// are traversed ` `   ``if` `(st.empty() || curr == n) ` `     ``return``; ` ` `  `   ``// Remove current item ` `   ``int` `x = st.top(); ` `   ``st.pop(); ` ` `  `   ``// Remove other items ` `   ``deleteMid(st, n, curr+1); ` ` `  `   ``// Put all items back except middle ` `   ``if` `(curr != n/2) ` `     ``st.push(x); ` `} ` ` `  `//Driver function to test above functions ` `int` `main() ` `{ ` `    ``stack<``char``> st; ` ` `  `    ``//push elements into the stack ` `    ``st.push(``'1'``); ` `    ``st.push(``'2'``); ` `    ``st.push(``'3'``); ` `    ``st.push(``'4'``); ` `    ``st.push(``'5'``); ` `    ``st.push(``'6'``); ` `    ``st.push(``'7'``); ` ` `  `    ``deleteMid(st, st.size()); ` ` `  `    ``// Printing stack after deletion ` `    ``// of middle. ` `    ``while` `(!st.empty()) ` `    ``{ ` `        ``char` `p=st.top(); ` `        ``st.pop(); ` `        ``cout << p << ``" "``; ` `    ``} ` `    ``return` `0; ` `} `

## Java

 `// Java code to delete middle of a stack ` `// without using additional data structure. ` `import` `java.io.*; ` `import` `java.util.*; ` ` `  `public` `class` `GFG { ` ` `  `    ``// Deletes middle of stack of size ` `    ``// n. Curr is current item number ` `    ``static` `void` `deleteMid(Stack st, ` `                              ``int` `n, ``int` `curr) ` `    ``{ ` `         `  `        ``// If stack is empty or all items ` `        ``// are traversed ` `        ``if` `(st.empty() || curr == n) ` `            ``return``; ` `         `  `        ``// Remove current item ` `        ``char` `x = st.pop(); ` `         `  `        ``// Remove other items ` `        ``deleteMid(st, n, curr+``1``); ` `         `  `        ``// Put all items back except middle ` `        ``if` `(curr != n/``2``) ` `            ``st.push(x); ` `    ``} ` `     `  `    ``// Driver function to test above functions ` `    ``public` `static` `void` `main(String args[])  ` `    ``{ ` `        ``Stack st = ` `                  ``new` `Stack(); ` `     `  `        ``// push elements into the stack ` `        ``st.push(``'1'``); ` `        ``st.push(``'2'``); ` `        ``st.push(``'3'``); ` `        ``st.push(``'4'``); ` `        ``st.push(``'5'``); ` `        ``st.push(``'6'``); ` `        ``st.push(``'7'``); ` `     `  `        ``deleteMid(st, st.size(), ``0``); ` `     `  `        ``// Printing stack after deletion ` `        ``// of middle. ` `        ``while` `(!st.empty()) ` `        ``{ ` `            ``char` `p=st.pop(); ` `            ``System.out.print(p + ``" "``); ` `        ``} ` `    ``} ` `} ` ` `  `// This code is contributed by  ` `// Manish Shaw (manishshaw1) `

## Python3

 `# Python3 code to delete middle of a stack ` `# without using additional data structure. ` `  `  `# Deletes middle of stack of size ` `# n. Curr is current item number ` `class` `Stack: ` `    ``def` `__init__(``self``): ` `        ``self``.items ``=` `[] ` `      `  `    ``def` `isEmpty(``self``): ` `        ``return` `self``.items ``=``=` `[] ` `      `  `    ``def` `push(``self``, item): ` `        ``self``.items.append(item) ` `      `  `    ``def` `pop(``self``): ` `        ``return` `self``.items.pop() ` `      `  `    ``def` `peek(``self``): ` `        ``return` `self``.items[``len``(``self``.items)``-``1``] ` `      `  `    ``def` `size(``self``): ` `        ``return` `len``(``self``.items)  ` `          `  `def` `deleteMid(st, n, curr) : ` ` `  `    ``# If stack is empty or all items ` `    ``# are traversed ` `    ``if` `(st.isEmpty() ``or` `curr ``=``=` `n) : ` `        ``return` `      `  `    ``# Remove current item ` `    ``x ``=` `st.peek() ` `    ``st.pop() ` `      `  `    ``# Remove other items ` `    ``deleteMid(st, n, curr``+``1``) ` `      `  `    ``# Put all items back except middle ` `    ``if` `(curr !``=` `int``(n``/``2``)) : ` `        ``st.push(x) ` `  `  `# Driver function to test above functions ` `st ``=` `Stack() ` `  `  `# push elements into the stack ` `st.push(``'1'``) ` `st.push(``'2'``) ` `st.push(``'3'``) ` `st.push(``'4'``) ` `st.push(``'5'``) ` `st.push(``'6'``) ` `st.push(``'7'``) ` `  `  `deleteMid(st, st.size(), ``0``) ` `  `  `# Printing stack after deletion ` `# of middle. ` `while` `(st.isEmpty() ``=``=` `False``) : ` `    ``p ``=` `st.peek() ` `    ``st.pop() ` `    ``print` `(``str``(p) ``+` `" "``, end``=``"") ` ` `  `# This code is contributed by ` `# Manish Shaw (manishshaw1) `

/div>

## C#

 `// C# code to delete middle of a stack ` `// without using additional data structure. ` `using` `System; ` `using` `System.Collections.Generic; ` ` `  `class` `GFG { ` `     `  `    ``// Deletes middle of stack of size ` `    ``// n. Curr is current item number ` `    ``static` `void` `deleteMid(Stack<``char``> st,  ` `                          ``int` `n,  ` `                          ``int` `curr = 0) ` `    ``{ ` `         `  `        ``// If stack is empty or all  ` `        ``// items are traversed ` `        ``if` `(st.Count == 0 || curr == n) ` `            ``return``; ` `         `  `        ``// Remove current item ` `        ``char` `x = st.Peek(); ` `        ``st.Pop(); ` `         `  `        ``// Remove other items ` `        ``deleteMid(st, n, curr+1); ` `         `  `        ``// Put all items  ` `        ``// back except middle ` `        ``if` `(curr != n / 2) ` `            ``st.Push(x); ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `Main()  ` `    ``{ ` `        ``Stack<``char``> st = ``new` `Stack<``char``>(); ` ` `  `        ``// push elements into the stack ` `        ``st.Push(``'1'``); ` `        ``st.Push(``'2'``); ` `        ``st.Push(``'3'``); ` `        ``st.Push(``'4'``); ` `        ``st.Push(``'5'``); ` `        ``st.Push(``'6'``); ` `        ``st.Push(``'7'``); ` `     `  `        ``deleteMid(st, st.Count); ` `     `  `        ``// Printing stack after  ` `        ``// deletion of middle. ` `        ``while` `(st.Count != 0) ` `        ``{ ` `            ``char` `p=st.Peek(); ` `            ``st.Pop(); ` `            ``Console.Write(p + ``" "``); ` `        ``} ` `    ``} ` `} ` ` `  `// This code is contributed by ` `// Manish Shaw (manishshaw1) `

Output:

```7 6 5 3 2 1
```

## tags:

Recursion Stack STL Recursion Stack STL