Fourth question: Rebuild the binary tree

Enter the results of pre-order traversal and middle-order traversal of a binary tree, and please rebuild the binary tree. Assume that the input result of pre-order traversal and middle-order traversal does not contain repeated numbers. For example, input the pre-order traversal sequence {1,2,4,7,3,5,6,8} and the middle-order traversal sequence {4,7,2,1,5,3,8,6}, then rebuild the binary tree and return.

example:

/** 
 * Refactor the binary tree 
 */  
public class Test4 {  
  
    public class TreeNode {  
        int val;  
        TreeNode left;  
        TreeNode right;  
        TreeNode(int x) {  
            val = x;  
        }  
    }  
  
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {  
        TreeNode root = resConstructBinaryTree(  
                pre,0,pre.length-1,  
                in,0,in.length-1);  
        return root;  
    }  
  
    public TreeNode resConstructBinaryTree(int [] pre,int startPre,int endPre,  
                                           int [] in,int startIn,int endIn){  
        if (startPre > endPre || startIn > endIn){  
            return null;  
        }  
        TreeNode node = new TreeNode(pre[startPre]);  
        for (int i = startIn; i <= endIn; i++){  
            if (in[i] == pre[startPre]){  
                node.left = resConstructBinaryTree(  
                        pre,startPre+1,startPre+i-startIn,  
                        in,startIn,i-1);  
                node.right = resConstructBinaryTree(  
                        pre,startPre+i-startIn+1,endPre,  
                        in,i+1,endIn);  
                break;  
            }  
        }  
        return node;  
    }  
  
}