static BST ReconstructBSTFromRange(int lowerBound, int upperBound,
List <int> preOrderTraversalValues,
TreeInfo currentSubtreeInfo)
{
if (currentSubtreeInfo.rootIdx == preOrderTraversalValues.Count)
{
return(null);
}
int rootValue = preOrderTraversalValues[currentSubtreeInfo.rootIdx];
if (rootValue < lowerBound || rootValue >= upperBound)
{
return(null);
}
currentSubtreeInfo.rootIdx += 1;
BST leftSubtree = ReconstructBSTFromRange(lowerBound, rootValue,
preOrderTraversalValues,
currentSubtreeInfo);
BST rightSubtree = ReconstructBSTFromRange(rootValue, upperBound,
preOrderTraversalValues,
currentSubtreeInfo);
BST bst = new BST(rootValue);
bst.left = leftSubtree;
bst.right = rightSubtree;
return(bst);
}
static BST ReconstructBst(List <int> preOrderTraversalValues)
{
TreeInfo treeInfo = new TreeInfo(0);
return(ReconstructBSTFromRange(Int32.MinValue, Int32.MaxValue, preOrderTraversalValues, treeInfo));
}
