重建二叉树

来源：互联网发布：数据库怎样设计表格编辑：程序博客网时间：2024/05/16 23:49

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {        TreeNode head = constructBinaryTree(pre,0,pre.length-1,in,0,in.length-1);        return head;    }        public TreeNode constructBinaryTree(int [] pre,int preStart,int preEnd,int [] in,int inStart,int inEnd){        if(preStart>preEnd || inStart>inEnd){            return null;        }else{            TreeNode node = new TreeNode(pre[preStart]);            for(int i=inStart; i<=inEnd; i++){                if(pre[preStart] == in[i]){                    node.left = constructBinaryTree(pre,preStart+1,preStart+i-inStart,in,inStart,i-1);                    node.right = constructBinaryTree(pre,preStart+i-inStart+1,preEnd,in,i+1,inEnd);                    break;                }            }            return node;        }    }}

0 0