1.BST->雙向連結串列

a.中序遍歷(有序)

b.插入節點

樹結構

package BSTLinkList;
public class TreeNode {
    int val = 0;
TreeNode left = null;
TreeNode right = null;
    public TreeNode(int val) {
        this.val = val;
}
}

public class BSTToLinkList {
    private TreeNode pre;
    private TreeNode head;
    public TreeNode Convert
 
(TreeNode root) {
        visit(root);
        return head;
}
    private void visit(TreeNode root){
        visit(root.left);
create(root);
visit(root.right);
}
    private void create(TreeNode treeNode){
        treeNode.left = pre;
        if (pre==null)
            head = treeNode;
        else
 
pre.right = treeNode;
pre = treeNode;
}
}

2.雙向連結串列->BST

public class LinkListToBST {
    TreeNode root;
    public TreeNode Convert(TreeNode head) {
        int cnt = 0;
TreeNode cur = head;
        while(cur!=null){
            cur = cur.right;
}
        return create(head,0,cnt-1);
}
    private TreeNode create
 
(TreeNode head, int left, int right){
        if (left>right)
            return null;
        int mid = left + (right - left)/2;
TreeNode leftChild = create(head,left,mid-1);
TreeNode parent = new TreeNode(head.val);
parent.left = leftChild;
head = head.right;
parent.right = create(head,mid+1,right);
        return parent;
}
}