Construct Binary Tree from Preorder and Inorder Traversal leetcode java

 1     public TreeNode buildTree(int[] preorder, int[] inorder) {
 2          int preLength = preorder.length;
 3          int inLength = inorder.length;
 4         return buildTree(preorder, 0, preLength-1, inorder, 0, inLength-1);
 5      }
 6    
 7     public TreeNode buildTree(int[] pre, int preStart, int preEnd, int[] in, int inStart, int inEnd){
 8          if(inStart > inEnd || preStart > preEnd)
 9              return null;
10              
11         int rootVal = pre[preStart];
12         int rootIndex = 0;
13         for(int i = inStart; i <= inEnd; i++){
14              if(in[i] == rootVal){
15                  rootIndex = i;
16                  break;
17              }
18          }
19        
20          int len = rootIndex - inStart;
21          TreeNode root = new TreeNode(rootVal);
22          root.left = buildTree(pre, preStart+1, preStart+len, in, inStart, rootIndex-1);
23          root.right = buildTree(pre, preStart+len+1, preEnd, in, rootIndex+1, inEnd);
24        
25         return root;
26      }