Construct Binary Tree from Preorder and Inorder Traversal

Description:

Given preorder and inorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

Code:

TreeNode * buildTree(vector<int>& preorder, int preBegin, int preEnd, vector<int>& inorder, int inBegin, int inEnd)

 {

    TreeNode*root =NULL;



    if (preEnd >= preBegin)

    {

        root = new TreeNode(preorder[preBegin]);

        int n = inEnd-inBegin+1;

        int rootIndex = 0;

        for (int i = inBegin; i <= inEnd; ++i)

        {

            if (inorder[i] == preorder[preBegin])

            {

                rootIndex = i;

                break;

            }

        }

        

        if (rootIndex!=inBegin)

        {

            root->left = buildTree(preorder, preBegin+1, preBegin+(rootIndex-inBegin), inorder, inBegin, rootIndex-1);

        }

        if (rootIndex!=inEnd)

        {

            root->right = buildTree(preorder, preBegin+1+(rootIndex-inBegin), preEnd, inorder, rootIndex+1, inEnd);

        }

    }

    return root;  

 }

    TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {

        return buildTree(preorder, 0, preorder.size()-1, inorder, 0, inorder.size()-1);

    }