public CustomNode <int> BuildSpecialTreeFromPreorderArray(int[] preArray, char[] LeafArray, int index)
{
if (index == preArray.Length)
{
CustomNode <int> nodenull = new CustomNode <int>();
nodenull.treenode = null;
nodenull.StartIndex = index;
return(nodenull);
}
KarthicBTNode <int> node = new KarthicBTNode <int>(preArray[index]);
int actualnodeindex = index;
index++;
CustomNode <int> custom = new CustomNode <int>();
custom.treenode = node;
custom.StartIndex = index;
//No leaf node
if (LeafArray[actualnodeindex] == 'N')
{
CustomNode <int> ltree = BuildSpecialTreeFromPreorderArray(preArray, LeafArray, index);
custom.treenode.Left = ltree.treenode;
CustomNode <int> rtree = BuildSpecialTreeFromPreorderArray(preArray, LeafArray, ltree.StartIndex);
custom.treenode.Right = rtree.treenode;
custom.StartIndex = rtree.StartIndex;
}
return(custom);
}
private void button5_Click(object sender, EventArgs e)
{
//source: http://www.geeksforgeeks.org/construct-a-special-tree-from-given-preorder-traversal/
int[] preorderarray = AlgorithmHelper.ConvertCommaSeparetedStringToInt(this.textBox5.Text);
char[] leafarray = AlgorithmHelper.ConvertCommaSeparetedStringToCharArray(this.textBox4.Text);
CustomNode <int> tree1 = new CustomNode <int>();
KarthicBinaryTree <int> tree = new KarthicBinaryTree <int>();
tree.Root = BuildSpecialTreeFromPreorderArray(preorderarray, leafarray, 0).treenode;
string output = tree.PreOrderTraversal(tree.Root);
bool result = String.Equals(this.textBox5.Text, output.Substring(0, output.LastIndexOf(',')), StringComparison.OrdinalIgnoreCase);
}
//souce: http://www.geeksforgeeks.org/construct-tree-from-given-inorder-and-preorder-traversal/
//Logic
//Inorder sequence: D B E A F C
//Preorder sequence: A B D E C F
//Given inorder and preorder sequence
//pick the first elemnet in preorder and build root element
//increment the value of preorderindex and maintain in the recurrsion..no bubble needed
//find the root element in the inorder array and get it's index
//the element to the left of index are leftsubtree and the element right of the index forms rightsubtree.
//recurse and build the tree in this logic
//The result tree
// //A
// / \
// / \
// B C
// / \ /
// / \ /
//D E F
public CustomNode <char> BuildBSTreeFromInOrderAndPreOrderArray(char[] preArray, int preIndex, char[] inArray, int inLow, int inHigh)
{
//base case
if (inHigh < inLow)
{
CustomNode <char> nodenull = new CustomNode <char>();
nodenull.treenode = null;
nodenull.StartIndex = preIndex;
return(nodenull);
}
//build the current node
KarthicBTNode <char> current = new KarthicBTNode <char>(Convert.ToChar(preArray[preIndex]));
//increment
preIndex++;
CustomNode <char> result = new CustomNode <char>();
result.treenode = current;
result.StartIndex = preIndex;
//after building the node..check for low and high
//for case low = 2 and high = 3..it mean this is leaf node..left and right will be null
//we stop the recursion here
if (inLow == inHigh)
{
return(result);
}
int indexofcurrent = SearchArray(inArray, current.Data, inLow, inHigh);
//divide the tree
CustomNode <char> lsubtree = BuildBSTreeFromInOrderAndPreOrderArray(preArray, preIndex, inArray, inLow, indexofcurrent - 1);
result.treenode.Left = lsubtree.treenode;
CustomNode <char> rsubtree = BuildBSTreeFromInOrderAndPreOrderArray(preArray, lsubtree.StartIndex, inArray, indexofcurrent + 1, inHigh);
result.treenode.Right = rsubtree.treenode;
result.StartIndex = rsubtree.StartIndex;
return(result);
}
private void button4_Click(object sender, EventArgs e)
{
char[] inorderarray = AlgorithmHelper.ConvertCommaSeparetedStringToCharArray(this.textBox2.Text);
char[] preorderarray = AlgorithmHelper.ConvertCommaSeparetedStringToCharArray(this.textBox3.Text);
CustomNode <char> tree = new CustomNode <char>();
KarthicBST <char> root = new KarthicBST <char>();
tree = BuildBSTreeFromInOrderAndPreOrderArray(preorderarray, 0, inorderarray, 0, inorderarray.Length - 1);
//The result tree
// //A
// / \
// / \
// B C
// / \ /
// / \ /
//D E F
}