# Find maximum and minimum element in binary tree without using recursion or stack or queue

Given a binary tree. The task is to find out the maximum and minimum element in a binary tree without using recursion or stack or queue i.e, space complexity should be O(1).

Examples:

```Input :
12
/     \
13       10
/     \
14       15
/   \     /  \
21   24   22   23

Output : Max element : 24
Min element : 10

Input :
12
/     \
19        82
/        /     \
41       15       95
\     /         /  \
2   21        7   16

Output : Max element : 95
Min element : 2
```

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

Approach :
1. Initialize current as root
2. Take to variable max and min
3. While current is not NULL

• If the current does not have left child
• Update variable max and min with current’s data if required
• Go to the right, i.e., current = current->right
• Else
• Make current as the right child of the rightmost
node in current’s left subtree
• Go to this left child, i.e., current = current->left

Below is the implementation of the above approach :

 `// C++ program find maximum and minimum element ` `#include ` `using` `namespace` `std; ` ` `  `// A Tree node ` `struct` `Node { ` `    ``int` `key; ` `    ``struct` `Node *left, *right; ` `}; ` ` `  `// Utility function to create a new node ` `Node* newNode(``int` `key) ` `{ ` `    ``Node* temp = ``new` `Node; ` `    ``temp->key = key; ` `    ``temp->left = temp->right = NULL; ` `    ``return` `(temp); ` `} ` ` `  ` `  `// Function to print a maximum and minimum element ` `// in a tree without recursion without stack ` `void` `printMinMax(Node* root) ` `{ ` `     `  `    ``if` `(root == NULL)  ` `    ``{ ` `        ``cout << ``"Tree is empty"``; ` `        ``return``; ` `    ``} ` `     `  `    ``Node* current = root; ` `     `  `    ``Node* pre; ` `     `  `    ``// Max variable for storing maximum value     ` `    ``int` `max_value = INT_MIN;  ` `     `  `    ``// Min variable for storing minimum value     ` `    ``int` `min_value = INT_MAX;  ` `     `  `     `  `    ``while` `(current != NULL) ` `    ``{  ` `        ``// If left child does nor exists ` `        ``if` `(current->left == NULL) ` `        ``{  ` `            ``max_value = max(max_value, current->key); ` `            ``min_value = min(min_value, current->key); ` `             `  `            ``current = current->right;  ` `        ``}  ` `        ``else`  `        ``{  ` `   `  `            ``// Find the inorder predecessor of current  ` `            ``pre = current->left;  ` `            ``while` `(pre->right != NULL && pre->right !=  ` `                                                 ``current)  ` `                ``pre = pre->right;  ` `   `  `            ``// Make current as the right child  ` `            ``// of its inorder predecessor  ` `            ``if` `(pre->right == NULL) ` `            ``{  ` `                ``pre->right = current;  ` `                ``current = current->left;  ` `            ``}  ` `   `  `            ``// Revert the changes made in the 'if' part to  ` `            ``// restore the original tree i.e., fix the  ` `            ``// right child of predecessor ` `            ``else`  `            ``{  ` `                ``pre->right = NULL;  ` `                 `  `                ``max_value = max(max_value, current->key); ` `                ``min_value = min(min_value, current->key); ` `             `  `                ``current = current->right;  ` `            ``} ``// End of if condition pre->right == NULL ` `             `  `        ``} ``// End of if condition current->left == NULL ` `         `  `    ``} ``// End of while  ` `     `  `    ``// Finally print max and min value ` `    ``cout << ``"Max Value is : "` `<< max_value << endl; ` `    ``cout << ``"Min Value is : "` `<< min_value << endl; ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``/* 15 ` `      ``/  \ ` `    ``19   11 ` `        ``/  \ ` `       ``25   5 ` `      ``/ \   / \ ` `    ``17  3  23  24 ` ` `  `    ``Let us create Binary Tree as shown ` `    ``above */` ` `  `    ``Node* root = newNode(15); ` `    ``root->left = newNode(19); ` `    ``root->right = newNode(11); ` ` `  `    ``root->right->left = newNode(25); ` `    ``root->right->right = newNode(5); ` ` `  `    ``root->right->left->left = newNode(17); ` `    ``root->right->left->right = newNode(3); ` `    ``root->right->right->left = newNode(23); ` `    ``root->right->right->right = newNode(24); ` `     `  `    ``// Function call for printing a max ` `    ``// and min element in a tree ` `    ``printMinMax(root); ` ` `  `    ``return` `0; ` `} `

Output :

```Max Value is : 25
Min Value is : 3
```

Space complexity: O(1)

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