Create a binary tree (recursion)

Stack is required for non-recursive Binary Tree creation, which is indeed too annoying. Here, only the method for recursively creating a binary tree is provided.

[Cpp]
# Include "stdafx. h"
# Include <iostream>
Using namespace std;
Typedef struct BiTreeNode
{
Char data;
BiTreeNode * left;
BiTreeNode * right;
} BiTreeNode, * BiTree;
 
// Both are created in the first order, that is, input in the first order, and input in the null node '#'
BiTreeNode * Create ()
{
Char ch;
Cin> ch;
BiTreeNode * root;
 
If (ch = '#')
Return NULL;
Else
{
Root = new BiTreeNode;
Root-> data = ch;
Root-> left = Create ();
Root-> right = Create ();
Return root;
}
}
 
Void CreateBiTree (BiTree & t) // required &
{
Char ch;
Cin> ch;
If (ch = '#')
T = NULL;
Else
{
T = new BiTreeNode;
If (! T)
Return;
T-> data = ch;
CreateBiTree (t-> left );
CreateBiTree (t-> right );
}
}
 
// First-order traversal
Void PreOrderTraverse (BiTreeNode * t)
{
If (t)
{
Cout <t-> data <"";
PreOrderTraverse (t-> left );
PreOrderTraverse (t-> right );
}

}
Int _ tmain (int argc, _ TCHAR * argv [])
{
BiTree t = NULL;
// T = Create (); // method 1
CreateBiTree (t); // method 2
PreOrderTraverse (t );
Cout <endl;
Return 0;
}
The preceding two methods are provided to create a binary tree recursively. The input must be a Complete Binary Tree.

Here we add a method to create a binary tree, as shown in the following code:
[Cpp]
// Node. cpp: defines the entry point of the console application.
//
 
# Include "stdafx. h"
# Include <iostream>
Using namespace std;
 
Struct node
{
Char value;
Node * left;
Node * right;
Node (char v, node * l = NULL, node * r = NULL): value (v), left (l), right (r)
{
}
};
 
Void preordertraverse (node * t)
{
If (t)
{
Cout <t-> value <"";
Preordertraverse (t-> left );
Preordertraverse (t-> right );
}

}
 
// Recursive deletion: delete a new node to prevent memory leakage
Void deletetree (node * t)
{
If (t-> left = NULL & t-> right = NULL)
{
Delete t;
T = NULL;
}
If (! T)
Return;
Else
{
If (t-> left)
Deletetree (t-> left );
If (t-> right)
Deletetree (t-> right );
If (t-> left = NULL & t-> right = NULL)
{
Delete t;
T = NULL;
}
}
}
 
Int _ tmain (int argc, _ TCHAR * argv [])
{
Node * t1 = new node ('7 ');
Node * t2 = new node ('8 ');
Node * t3 = new node ('5', t1, t2 );
Node * t4 = new node ('4 ');
Node * t5 = new node ('6 ');
Node * t6 = new node ('2', t4, t3 );
Node * t7 = new node ('3', NULL, t5 );
Node * t8 = new node ('1', t6, t7 );
 
Preordertraverse (t8 );

Deletetree (t8 );
Www.2cto.com
Cout <endl;
Return 0;
}

This method is convenient to process the relationship between nodes through the constructor method.