Private Sub Form1_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
Select Case (e.KeyCode)
Case Keys.A
Case Keys.B
Case Keys.C
Case Keys.D
Case Else
End Select
End Sub
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Trie
{
public class TrieNode
{
public string RemainingKey = "";
public string Value = null;
public TrieNode[] Children = null;
// Add a value to this node's subtrie.
public void AddValue(string newKey, string newValue)
{
int index;
// If the remaining new key is not blank and matches
// the remaining node key, place the value here.
if ((newKey.Length > 0) && (newKey == RemainingKey))
{
Value = newValue;
return;
}
// If the remaining new key is blank and
// so is the remaining node key, place the value here.
if ((newKey.Length == 0) && (RemainingKey.Length == 0))
{
Value = newValue;
return;
}
// If the new key is blank but the node's remaining key isn't blank,
// move the node's remaining key into a child and place the value here.
if ((newKey.Length == 0) && (RemainingKey.Length > 0))
{
// This must be a leaf node so give it children.
Children = new TrieNode[26];
index = RemainingKey[0] - 'A';
Children[index] = new TrieNode();
Children[index].RemainingKey = RemainingKey.Substring(1);
Children[index].Value = Value;
RemainingKey = "";
Value = newValue;
return;
}
// We need a child node.
if (Children == null)
{
// Make the children.
Children = new TrieNode[26];
// See if we have a remaining key.
if (RemainingKey.Length > 0)
{
// Move this into the appropriate child.
index = RemainingKey[0] - 'A';
Children[index] = new TrieNode();
Children[index].RemainingKey = RemainingKey.Substring(1);
Children[index].Value = Value;
RemainingKey = "";
Value = null;
}
}
// Search the appropriate subtrie.
index = newKey[0] - 'A';
if (Children[index] == null)
{
// This child doesn't exist. Make it and
// let it represent the rest of the new key.
Children[index] = new TrieNode();
Children[index].RemainingKey = newKey.Substring(1);
Children[index].Value = newValue;
return;
}
// Search the appropriate subtrie.
Children[index].AddValue(newKey.Substring(1), newValue);
}
// Find a value in this node's subtrie.
public string FindValue(string targetKey)
{
// If the remaining key matches the
// remaining node key, return this node's value.
if (targetKey == RemainingKey) return Value;
// Search the appropriate child.
if (Children == null) return null;
int index = targetKey[0] - 'A';
if (Children[index] == null) return null;
return Children[index].FindValue(targetKey.Substring(1));
}
// Return a textual representation of this subtrie.
public override string ToString()
{
return MakeString('-', 0);
}
// Return a textual representation for this subtrie.
// Variable letter is this node's letter.
private string MakeString(char letter, int indent)
{
// Start with our value.
string result = new string(' ', indent);
result += letter;
if (RemainingKey.Length > 0) result += " -> " + RemainingKey;
if (Value != null) result += " (" + Value + ")";
result += Environment.NewLine;
// Add the child values if we have any.
if (Children != null)
{
for (int i = 0; i < 26; i++)
{
if (Children[i] != null)
{
char ch = (char)('A' + i);
result += Children[i].MakeString(ch, indent + 2);
}
}
}
return result;
}
}
}
Code (C#)
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Trie
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
// The root of the trie.
private TrieNode Root = new TrieNode();
// Add a value to the trie.
private void addButton_Click(object sender, EventArgs e)
{
string key = keyTextBox.Text.ToUpper();
if (key.Length == 0)
{
MessageBox.Show("Key must not be blank");
keyTextBox.Focus();
return;
}
string value = valueTextBox.Text;
if (value.Length == 0)
{
MessageBox.Show("Value must not be blank");
valueTextBox.Focus();
return;
}
Root.AddValue(key, value);
trieTextBox.Text = Root.ToString();
trieTextBox.Select(0, 0);
keyTextBox.Clear();
keyTextBox.Focus();
valueTextBox.Clear();
}
// Find a value to the trie.
private void findButton_Click(object sender, EventArgs e)
{
string key = keyTextBox.Text.ToUpper();
string value = Root.FindValue(key);
if (value == null) valueTextBox.Text = "null";
else valueTextBox.Text = value;
trieTextBox.Text = Root.ToString();
trieTextBox.Select(0, 0);
keyTextBox.Focus();
keyTextBox.Select(0, keyTextBox.Text.Length);
}
// Uncomment to build a tree at startup for testing.
private void Form1_Load(object sender, EventArgs e)
{
//Root.AddValue("หำ", "29");
//Root.AddValue("หำน้อย", "36");
//Root.AddValue("WANTED", "10");
//Root.AddValue("WAN", "18");
//Root.AddValue("หำเล็ก", "72");
trieTextBox.Text = Root.ToString();
trieTextBox.Select(0, 0);
}
}
}
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