通过两种深度优先遍历方式重建二叉树或者得到其余一种遍历方式

 1 /**
 2  * 二叉树节点的定义
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class reConstruct{
11     public TreeNode reConstructBinaryTree(int [] pre, int [] in){
12         TreeNode treeNode = reConstruct(pre,0,pre.length-1,in,0,in.length-1);
13         return treeNode;
14     }
15 
16     private TreeNode reConstruct(int[] pre,int startPre,int endPre,int[] in,int startIn,int endIn){
17         if(startPre>endPre || startIn>endIn){
18             return null;
19         }
20         TreeNode treeNode = new TreeNode(pre[startPre]);
21         for(int i=startIn;i<=endIn;i++){
22             if(in[i]==pre[startPre]){
23                 treeNode.left = reConstruct(pre,startPre+1,startPre+i-startIn,in,startIn,i-1);
24                 treeNode.right = reConstruct(pre,startPre+i-startIn+1,endPre,in,i+1,endIn);
25                 break;
26             }
27         }
28         return treeNode;
29     }
30 }