Java creates a binary tree to store the numbers in the array into the binary tree in sequence, and uses the first, last, and middle order for traversal respectively;

 

Create a binary tree using Java to store the number in the array into a binary tree in sequence. If the value is negative or zero, the corresponding node is empty.

 

Define the structure of a binary tree

Public class bitree {
Int data;
Bitree left;
Bitree right;
Int I; // the location where the value of this node is stored in the array;
Public bitree (){

}


Public bitree (int I ){
This. I = I;
}
Public bitree (INT data, bitree L, bitree R ){
This. Data = data;
This. Left = L;
This. Right = R;
}
Public void print (){
System. Out. Print (this. Data + ",");
}
}

 

 

Interface

Public interface visittreeinterface {
Public bitree creatroot (bitree node); // create a root node
Public bitree creatleft (bitree node); // Insert the left Node
Public bitree creatright (bitree node); // Insert the right Node
Public void preorder (bitree node); // traverses Binary Trees in ascending order
Public void lastorder (bitree node); // post-order traversal
Public void midorder (bitree node); // supports sequential traversal.

}

Classes that implement interfaces

Public class creattree implements visittreeinterface {

Int [] B;

Public creattree (INT [] ){
This. B =;
 
}

Public bitree creatroot (bitree node) {// create a root node
If (node. I <B. Length ){
If (B [node. I] <= 0)
Node = NULL;
Else if (node! = NULL ){
Node. Data = B [node. I];
System. Out. println (node. I + "" + node. data );
Node. Left = creatleft (node );
Node. Right = creatright (node );

}
}
Return node;
 
}

Public bitree creatleft (bitree node) {// left Node
If (node! = NULL)
{
Node. Left = new bitree ();
Node. Left. I = 2 * node. I + 1; // if the position of the root node in the array is I, the left node is 2 * I + 1

Creatroot (node. Left); // call recursion;
}
Return node. Left;
}

Public bitree creatright (bitree node) {// right Node
If (node! = NULL)
{
Node. Right = new bitree ();
Node. Right. I = 2 * node. I + 2;
Creatroot (node. Right );
}
Return node. Right;
}

Public void preorder (bitree node ){
If (node! = NULL ){
Node. Print ();
Preorder (node. Left );
Preorder (node. Right );
}
}

Public void lastorder (bitree node ){
If (node! = NULL ){
Lastorder (node. Left );
Lastorder (node. Right );
Node. Print ();

}
 
}

Public void midorder (bitree node ){
If (node! = NULL ){
Midorder (node. Left );
Node. Print ();
Midorder (node. Right );
}

}
}

 

Create a binary tree and traverse it

Public class main {
Public static void main (string [] ARGs ){
Int [] B = {,-6, 5, 9, 10 };
Bitree node = new bitree (0 );
Bitree Bt;
Creattree Ct = new creattree (B );
Bt = CT. creatroot (node );
Ct. preorder (BT );
System. Out. Print ("/N ");
Ct. lastorder (BT );
System. Out. Print ("/N ");
Ct. midorder (BT );
System. Out. Print ("/N ");

}

}