leetcode 66: Convert Sorted List to Binary Search Tree

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原文链接：http://www.cnblogs.com/xishibean/archive/2013/01/31/2951321.html

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#java

本文详细介绍了如何将一个已排序的链表转换为一个高度平衡的二叉搜索树，并通过示例代码展示了实现过程。

Convert Sorted List to Binary Search TreeOct 3 '12

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

uncompleted

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; next = null; }
 * }
 */
/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode sortedListToBST(ListNode head) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if( head==null ) return null;
        ListNode p = head;
        while(p.next!=null) {
            p = p.next;
        }
        return bstRec(head, p);
    }
    
    private TreeNode bstRec(ListNode low, ListNode high) {
        if(low == high) return null;
        ListNode p=low, q=low;
        
        while(q!=high) {
            if( q.next == null ) break;
            q = q.next.next;
            p = p.next;
        }
        
        TreeNode head = new TreeNode( p.next.val );
        head.left = bstRec(low, p);
        
        if(p.next!=null){
            bstRec(p.next,high);
        }
        
        return head;
    }
}

转载于:https://www.cnblogs.com/xishibean/archive/2013/01/31/2951321.html