public BSTReconstruct()
{
var preOrderTraversalValues = new int[] { 10, 4, 2, 1, 5, 17, 19, 18 };
var treeInfo = new TreeInfoForRConstruct(0);
var lowerIdx = int.MinValue;
var upperIdx = int.MaxValue;
reconstructBSTFromRange(lowerIdx, upperIdx, preOrderTraversalValues, treeInfo);
}
private BST reconstructBSTFromRange(int lowerIdx, int upperIdx, int[] preOrderTraversalValues, TreeInfoForRConstruct currentSubTreeInfo)
{
if (currentSubTreeInfo.RootIdx == preOrderTraversalValues.Length)
{
return(null); //This means we have finished all of the nodes
}
var rootValue = preOrderTraversalValues[currentSubTreeInfo.RootIdx];
if (rootValue < lowerIdx || rootValue >= upperIdx)
{
return(null); // This node is not valid to be added. Also take care of duplicates
}
currentSubTreeInfo.RootIdx += 1;
var leftSubtree = reconstructBSTFromRange(lowerIdx, rootValue, preOrderTraversalValues, currentSubTreeInfo);
var rightSubtree = reconstructBSTFromRange(rootValue, upperIdx, preOrderTraversalValues, currentSubTreeInfo);
var newBST = new BST(rootValue);
newBST.left = leftSubtree;
newBST.right = rightSubtree;
return(newBST);
}
