// PreOrder A B C D E F

// InOrder C B D A E F

// Build Tree

public static Node GetTree(char[] PreOrder, char[] InOrder, int index = 0)



{
Node root = new Node();



root.data = PreOrder[index];
int inIndex = Array.IndexOf(InOrder, PreOrder[index]);

if ( index + 1 < PreOrder.Length && IsLeftSubtree(PreOrder[index + 1], InOrder, inIndex) == true)



root.left = GetTree(PreOrder, InOrder, index + 1);
else

root.left = null;

if (inIndex + 1 < InOrder.Length && IsPredecessor(InOrder[inIndex + 1], PreOrder, index) == false)



root.right = GetTree(PreOrder, InOrder, inIndex + 1);
else

root.right = null;

return root;



}
private static bool IsPredecessor(char c, char[] PreOrder, int index)



{
return Array.IndexOf(PreOrder, c) < index;



}
private static bool IsLeftSubtree(char c, char[] InOrder, int index)



{
return Array.IndexOf(InOrder, c) < index;



}