题目描述
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。
代码:
<span style="font-size:18px;">/** * 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 root=reConstructBinaryTree(pre,0,pre.length-1,in,0,in.length-1); return root; } //前序遍历{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6} private TreeNode reConstructBinaryTree(int [] pre,int startPre,int endPre,int [] in,int startIn,int endIn) { if(startPre>endPre||startIn>endIn) return null; TreeNode root=new TreeNode(pre[startPre]); for(int i=startIn;i<=endIn;i++) if(pre[startPre]==in[i]){ root.left=reConstructBinaryTree(pre,startPre+1,startPre+i-startIn,in,startIn,i-1); root.right=reConstructBinaryTree(pre,i+startPre+1-startIn,endPre,in,i+1,endIn); } return root; } }</span>
时间: 2024-10-10 01:58:00