Construct Binary Tree from Inorder and PostOrder LeetCode

The last element from postOrder is the root value.

Find the last element from inOrder, Will get the length of subTrees.

public TreeNode buildTree(int[] inorder, int[] postorder) {

        if (inorder == null || postorder == null) return null;

        if (inorder.length == 0 || postorder.length == 0) return null;

        return buildTree(inorder, 0, inorder.length-1, postorder, 0, postorder.length-1);

}

private TreeNode buildTree(int[] inorder, int start1, int end1, int[] postorder, int start2, int end2) {

   if (start1 > end1 || start2 > end2) return null;

   int currentValue = postorder[end2];

   TreeNode currRoot = new TreeNode(currentValue);

   int k = start1;

   for (; k < inorder.length; k++) {

       if (inorder[k] == currentValue) break;

   }

   currRoot.left = buildTree(inorder, start1, k-1, postorder, start2, end2-end1+k-1);

   currRoot.right = buildTree(inorder, k+1, end1, postorder, end2-end1+k, end2-1);

   return currRoot;

}