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) { int length=pre.length; int length1=in.length; if(pre==null||in==null||length<=0||length1<=0)return null; return ConstructCore(pre,0,length-1,in,0,length1-1); } private TreeNode ConstructCore(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(in[i]==pre[startpre]){ root.left=ConstructCore(pre,startpre+1,startpre+i-startin,in,startin,i-1); root.right=ConstructCore(pre,startpre+i-startin+1,endpre,in,i+1,endin); } } return root; } }
