如何创建一个递归方法来生成二叉树?

Question

当右侧的递归迭代到达状态 2 并返回时，问题就来了，因为父亲取了一个他不应该取的值。

这是我的节点创建器类，它有左右两边：

public class TreeNodo{
public byte vectorPosible[]; 
public int stage; //my stages and index posision of array
public TreeNodo right; // if goes to right mean 1, in index posision of array
public TreeNodo left; // if goes to right mean 0, in the index posision of array
//contructor
public TreeNodo(byte vectorPosible[], int currentStage){
this.vectorPosible=vectorPosible;
this.stage=currentStage; 
this.right=null;
this.left=null;
}
}

这是我的递归类，我初始化构造函数，在这一刻我开始递归：

public class SolutionTree{
TreeNodo root; //it saves the vector [-1,-1] that its initial stage
//contructor 
public SolutionTree(byte vectorPosible[], int currentStage){
this.root=new TreeNodo(vectorPosible, currentStage);
this.generarTreePSR(root, vectorPosible, vectorPosible.length, currentStage+1); //Generate a Tree of Possible Solutions Recursively
}
//Metod to insert Tree Node Recursively
public static void generarTreePSR(TreeNode father,byte vectorPosible[],int maxStage, int currentStage){  //in this case maxStage is 2
TreeNode newNode= new TreeNode(vectorPosible, currentStage);
System.out.println("newNode.left: "+(newNode.left==null));
System.out.println("newNode.right: "+(newNode.right==null));
System.out.println();       
System.out.println("newNode stage: "+newNode.stage);
if(newNode.stage==maxStage){ //BASE CASE, IF STAGE == 2
System.out.println("Reached this stage max: "+newNode.stage);
System.out.println("I return");
return;
}else{ // it isn't in the base case, so tree follow growing
System.out.print("Look i'm father and i'm before of left, my vector is: ");
for (int j=0;j<father.vectorPosible.length;j++) { //i show the father vector's
System.out.print(father.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();

System.out.println("I'm before if Left, and it is: "+(father.left==null));
if(father.left==null){
newNode.vectorPosible[newNode.stage]=0; //insert 0
father.left=newNode; //asign node
for (int j=0;j<father.left.vectorPosible.length;j++) { //i show what i insert into this left node
System.out.print(father.left.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("Nodo added left with success");
System.out.println();
generarTreePSR(father.left, father.left.vectorPosible, maxStage, currentStage+1);
}
System.out.print("Look i'm father and i'm before of right, my vector is: ");
for (int j=0;j<father.vectorPosible.length;j++) { //i show the father vector's
System.out.print(father.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("I'm before if Right, and it is: "+(father.right==null));
if(father.right==null){
newNode.vectorPosible[newNode.stage]=1; //insert 1
father.right=newNode; //asign node
for (int j=0;j<father.right.vectorPosible.length;j++) {  //i show what i insert into this right node
System.out.print(father.right.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("Nodo added right with success");
System.out.println();
generarTreePSR(father.right, father.right.vectorPosible, maxStage, currentStage+1);
}
return;
}
}
}

这是我的主类，用我想要的向量运行它：

public class TryTree{
public static void main(String[] args) {
byte vectorPosibles[]={-1,-1};
SolutionTree tree=new SolutionTree(vectorPosibles); //tree of posible solutions and it need to pass a vector [-1,-1]
}
}

它并没有生成我需要的所有节点。查看所有节点的图像： 带有节点的图像我需要什么 ， int 我需要递归地而不是扫描。

Answer 1

为此，您需要在构造函数 TreeNode 中使用它： System.arraycopy(vectorPosible， 0， this.vectorPosible， 0， vectorPosible.length(;

然后代码将如下所示：

public class TreeNodo{
public byte vectorPosible[]; 
public int stage; //my stages and index posision of array
public TreeNodo right; // if goes to right mean 1, in index posision of array
public TreeNodo left; // if goes to right mean 0, in the index posision of array
//contructor
public TreeNodo(byte vectorPosible[], int currentStage){
this.vectorPosible=vectorPosible;
this.stage=currentStage; 
this.right=null;
this.left=null;
}
}

除此之外，您必须在 SolutionTree 中声明两个 newNode(1 和 2(，因为如果您声明一个，它将使用相同的向量引用。然后代码将如下所示：

public class SolutionTree{
TreeNodo root; //it saves the vector [-1,-1] that its initial stage
//contructor 
public SolutionTree(byte vectorPosible[], int currentStage){
this.root=new TreeNodo(vectorPosible, currentStage);
this.generarTreePSR(root, vectorPosible, vectorPosible.length, currentStage+1); //Generate a Tree of Possible Solutions Recursively
}
//Metod to insert Tree Node Recursively
public static void generarTreePSR(TreeNode father,byte vectorPosible[],int maxStage, int currentStage){  //in this case maxStage is 2
if(currentStage==maxStage){ //BASE CASE, IF STAGE == 2
System.out.println("Reached this stage max: "+currentStage);
System.out.println("I return");
return;
}else{ // it isn't in the base case, so tree follow growing
//NEW TREE NODE1
TreeNode newNode1=new TreeNode(father.getVectorPos(), currentStage); //<------Solucion
newNode1.stage=currentStage;
//NEW TREE NODE2
TreeNode newNode2= new TreeNode(father.getVectorPos(), currentStage); //<------Solucion
newNode2.stage=currentStage;

System.out.print("Look i'm father and i'm before of left, my vector is: ");
for (int j=0;j<father.vectorPosible.length;j++) { //i show the father vector's
System.out.print(father.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();

System.out.println("I'm before if Left, and it is: "+(father.left==null));
if(father.left==null){
newNode.vectorPosible[newNode.stage]=0; //insert 0
father.left=newNode; //asign node
for (int j=0;j<father.left.vectorPosible.length;j++) { //i show what i insert into this left node
System.out.print(father.left.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("Nodo added left with success");
System.out.println();
generarTreePSR(father.left, father.left.vectorPosible, maxStage, currentStage+1);
}
System.out.print("Look i'm father and i'm before of right, my vector is: ");
for (int j=0;j<father.vectorPosible.length;j++) { //i show the father vector's
System.out.print(father.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("I'm before if Right, and it is: "+(father.right==null));
if(father.right==null){
newNode.vectorPosible[newNode.stage]=1; //insert 1
father.right=newNode; //asign node
for (int j=0;j<father.right.vectorPosible.length;j++) {  //i show what i insert into this right node
System.out.print(father.right.vectorPosible[j]);
System.out.print(" ");
}
System.out.println();
System.out.println("Nodo added right with success");
System.out.println();
generarTreePSR(father.right, father.right.vectorPosible, maxStage, currentStage+1);
}
return;
}
}
}