Java从三元树创建双向链接列表
在此程序中，给定的三叉树将转换为相应的双向链表。
三元树是一个分层的数据结构，其中每个节点最多可以有三个孩子。这可以通过以一种顺序方式遍历三叉树来完成，即根->左子->中间子->右子。首先，遍历根节点并将其添加到列表中。然后，分别添加其左，中和右子树。
三叉树:
对应的双向链接列表:
算法
定义一个Node类，该类代表三叉树中的一个节点。它具有四个属性: data，left，middle和right，其中left，middle和right代表节点的三个子代。
根将代表三元树的根。头和尾节点代表双向链表的头和尾。
convertTernaryToDLL()将给定的三叉树转换为相应的双向链表。 左，中和右节点代表给定节点的子节点。 如果节点不为空，则该节点将被插入列表。 如果列表为空，头和尾都将指向一个节点。 如果列表不为空，则该节点将插入列表的末尾。在这里，左，右指针将代表双向链表的上一个和下一个指针。中间不会指向任何内容，因此，只需将其设置为null。 将节点成功添加到列表中后，递归调用convertTernaryToDLL()以将给定节点的左，中和右子级添加到列表中。
a.displayDLL()将显示列表中存在的所有节点。
定义一个新节点"当前"，该节点将指向头部。
打印current.data直到current指向null。
当前每次迭代将指向列表中的下一个节点。
程序:
public class TernaryTreeToDLL {
//Represent a node of ternary tree
public static class Node{
int data;
Node left;
Node middle;
Node right;
public Node(int data) {
this.data = data;
}
}
//Represent the root of the ternary tree
public Node root;
//Represent the head and tail of the doubly linked list
Node head, tail = null;
//convertTernaryToDLL() will convert the given ternary tree to corresponding doubly linked list
public void convertTernaryToDLL(Node node) {
//Checks whether node is null
if(node == null)
return;
//Keep three pointers to all three children
Node left = node.left;
Node middle = node.middle;
Node right = node.right;
//if list is empty then, add node as head of the list
if(head == null) {
//Both head and tail will point to node
head = tail = node;
node.middle = null;
//head's left will point to null
head.left = null;
//tail's right will point to null, as it is the last node of the list
tail.right = null;
}
//Otherwise, add node to the end of the list
else {
//node will be added after tail such that tail's right will point to node
tail.right = node;
//node's left will point to tail
node.left = tail;
node.middle = null;
//node will become new tail
tail = node;
//As it is last node, tails right will point to null
tail.right = null;
}
//Add left child of current node to the list
convertTernaryToDLL(left);
//Then, add middle child of current node to the list
convertTernaryToDLL(middle);
//Then, add right child of current node to the list
convertTernaryToDLL(right);
}
//displayDLL() will print out the nodes of the list
public void displayDLL() {
//Node current will point to head
Node current = head;
if(head == null) {
System.out.println("List is empty");
return;
}
System.out.println("Nodes of generated doubly linked list: ");
while(current != null) {
//Prints each node by incrementing the pointer.
System.out.print(current.data + " ");
current = current.right;
}
System.out.println();
}
public static void main(String[] args) {
TernaryTreeToDLL tree = new TernaryTreeToDLL();
//Add nodes to the ternary tree
tree.root = new Node(5);
tree.root.left = new Node(10);
tree.root.middle = new Node(12);
tree.root.right = new Node(15);
tree.root.left.left = new Node(20);
tree.root.left.middle = new Node(40);
tree.root.left.right = new Node(50);
tree.root.middle.left = new Node(24);
tree.root.middle.middle = new Node(36);
tree.root.middle.right = new Node(48);
tree.root.right.left = new Node(30);
tree.root.right.middle = new Node(45);
tree.root.right.right = new Node(60);
//Converts the given ternary tree to doubly linked list
tree.convertTernaryToDLL(tree.root);
//Displays the nodes present in the list
tree.displayDLL();
}
}
输出:
Nodes of generated doubly linked list:
5 10 20 40 50 12 24 36 48 15 30 45 60
