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TrieOperation.cs
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141 lines (118 loc) · 4.08 KB
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using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Algorithms.Problem.Tries
{
public class TrieNode
{
private int SIZE = 26;
public TrieNode[] Children;
public bool isWordEnd;
public TrieNode()
{
this.Children = new TrieNode[SIZE];
this.isWordEnd = false;
}
}
[TestClass]
public class TrieOperation
{
public void Insert(TrieNode root, string value)
{
TrieNode node = root;
for(int i=0;i < value.Length; i++)
{
int index = value[i] - 'a';
if (node != null && node.Children[index] == null)
{
node.Children[index] = new TrieNode();
}
node = node.Children[index];
}
node.isWordEnd = true;
}
public void Delete(TrieNode root, string value)
{
this.DeleteHelper(root, value, 0);
}
public void DeleteHelper(TrieNode root, string value, int position)
{
if (root == null) return;
if (root.isWordEnd && position == value.Length)
{
return;
}
int index = value[position] - 'a';
if (root.Children[index] != null)
{
this.DeleteHelper(root.Children[index], value, position + 1);
if (root != null)
{
int index1 = value[position] - 'a';
TrieNode child = root.Children[index1];
if (!this.HasChildNodes(child))
{
// dont delete if it's the end of some other word.
// but delete if it's the end of the current string.
// the position will be equal to the value.Length - 1 if it's the end of current string (when using recursion the postion will be value of the last char in the string)
if (child.isWordEnd && position == value.Length - 1)
{
root.Children[index1] = null;
}
}
}
}
}
public bool HasChildNodes(TrieNode node)
{
for(int i=0; i< node.Children.Length;i++)
{
if (node.Children[i] != null)
{
return true;
}
}
return false;
}
public bool Search(TrieNode root, string value)
{
TrieNode node = root;
for(int i=0; i< value.Length; i++)
{
int index = value[i] - 'a';
if (node.Children[index] == null)
{
return false;
}
node = node.Children[index];
}
return node != null && node.isWordEnd;
}
[TestMethod]
public void TestTrieInsert()
{
// create root node.
TrieNode root = new TrieNode();
// insert the strings as dictionary
TrieOperation operation = new TrieOperation();
operation.Insert(root, "abc");
operation.Insert(root, "abcd");
operation.Insert(root, "aa");
operation.Insert(root, "abbbaba");
// assert for search operation
Assert.IsTrue(operation.Search(root, "abc"));
Assert.IsTrue(operation.Search(root, "abcd"));
Assert.IsTrue(operation.Search(root, "abbbaba"));
Assert.IsFalse(operation.Search(root, "abb"));
// delete abc from Trie node
operation.Delete(root, "abcd");
// assert for search operation.
Assert.IsFalse(operation.Search(root, "abcd"));
Assert.IsTrue(operation.Search(root, "abc"));
Assert.IsTrue(operation.Search(root, "abbbaba"));
}
}
}