public void TrieDeleteTest()
{
var trie = new WordTrie();
trie.Insert("ab");
trie.Insert("abc");
trie.Insert("abd");
trie.Delete("ab");
Assert.False(trie.Search("ab"));
Assert.True(trie.Search("abc"));
Assert.True(trie.Search("abd"));
trie.Delete("abc");
Assert.False(trie.Search("ab"));
Assert.False(trie.Search("abc"));
Assert.True(trie.Search("abd"));
trie.Delete("abd");
Assert.False(trie.Search("ab"));
Assert.False(trie.Search("abc"));
Assert.False(trie.Search("abd"));
}