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。
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public TreeNode solve(int pre[],int in[],int root,int inL,int inR){
if(inL>=inR) return null;
TreeNode tr=new TreeNode(pre[root]);
for(int i=inL;i<inR;i++){
if(in[i]==pre[root]){
root++;
tr.left=solve(pre,in,root,inL,i);
tr.right=solve(pre,in,root+i-inL,i+1,inR);
break;
}
}
return tr;
}
public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
return solve(pre,in,0,0,in.length);
}
}