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; }
* }
*/
import java.util.*;
public class Solution {
public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
if(pre.length == 0 || in.length == 0) {
return null;
}
TreeNode root = new TreeNode(pre[0]);
for(int i = 0; i<in.length;i++) {
if(in[i] == pre[0]) {
// 递归获取左节点
root.left = reConstructBinaryTree(
Arrays.copyOfRange(pre, 1, i+1),
Arrays.copyOfRange(in, 0, i));
// 递归获取右节点
root.right = reConstructBinaryTree(
Arrays.copyOfRange(pre, i+1, pre.length),
Arrays.copyOfRange(in, i+1, in.length));
}
}
return root;
}
}
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