* 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。题解：
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) {val = x;}
* }
*/
import java.util.Arrays;
public class Solution {
public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
int length = pre.length;
if (length == 0){
return null;
}
TreeNode treeNode = new TreeNode(pre[0]);
int index = getIndexByValue(in,pre[0]);
if (index != 0){
treeNode.left = reConstructBinaryTree(Arrays.copyOfRange(pre,1,index+1),Arrays.copyOfRange(in,0,index));
}
if (index != length){
treeNode.right = reConstructBinaryTree(Arrays.copyOfRange(pre,index +1,length),Arrays.copyOfRange(in,index +1,length));
}
return treeNode;
}
private int getIndexByValue(int [] array,int value){
for (int i = 0;i<array.length;i++){
if (array[i] == value){
return i;
}
}
return -1;
}
}