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Trie.java
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112 lines (96 loc) · 2.54 KB
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class TrieNode
{
char _c;
boolean _worEnd = false;
TrieNode[] _child = new TrieNode[26];
public TrieNode()
{
}
public TrieNode( char c )
{
_c = c;
}
}
public class Trie
{
TrieNode _root;
public Trie()
{
_root = new TrieNode();
}
// Inserts a word into the trie
public void insert( String word )
{
TrieNode traverse = _root;
for ( char c : word.toCharArray() )
{
if ( traverse._child[c - 'a'] == null )
traverse._child[c - 'a'] = new TrieNode( c );
traverse = traverse._child[c - 'a'];
}
traverse._worEnd = true;
}
// Returns if the word is in the trie.
public boolean search( String word )
{
TrieNode traverse = _root;
for ( char c : word.toCharArray() )
{
if ( traverse._child[c - 'a'] == null )
return false;
traverse = traverse._child[c - 'a'];
}
if ( traverse._worEnd )
return true;
return false;
}
// Returns if there is any word in the trie
// that starts with the given prefix.
public boolean startsWith( String prefix )
{
TrieNode traverse = _root;
for ( char c : prefix.toCharArray() )
{
if ( traverse._child[c - 'a'] == null )
return false;
traverse = traverse._child[c - 'a'];
}
return true;
}
void rootPrint( String prefix, TrieNode root )
{
TrieNode traverse = root;
for ( TrieNode t : traverse._child )
{
if ( t == null )
continue;
String nextPrefix = prefix + String.valueOf( t._c );
if ( t._worEnd )
System.out.println( nextPrefix );
rootPrint( nextPrefix, t );
}
}
public static void main( String[] args )
{
String[] ops = { "Trie", "insert", "insert", "insert", "insert", "insert", "insert", "search", "search", "search", "search", "search",
"search", "search", "search", "search", "startsWith", "startsWith", "startsWith", "startsWith", "startsWith", "startsWith",
"startsWith", "startsWith", "startsWith" };
String[][] vals = { {}, { "app" }, { "apple" }, { "beer" }, { "add" }, { "jam" }, { "rental" }, { "apps" }, { "app" }, { "ad" },
{ "applepie" }, { "rest" }, { "jan" }, { "rent" }, { "beer" }, { "jam" }, { "apps" }, { "app" }, { "ad" }, { "applepie" }, { "rest" },
{ "jan" }, { "rent" }, { "beer" }, { "jam" } };
Trie t = new Trie();
System.out.println( "null" );
for ( int i = 1; i < ops.length; i++ )
{
if ( ops[i].equals( "insert" ) )
{
t.insert( vals[i][0] );
System.out.println( "null" );
}
if ( ops[i].equals( "search" ) )
System.out.println( t.search( vals[i][0] ) );
if ( ops[i].equals( "startsWith" ) )
System.out.println( t.startsWith( vals[i][0] ) );
}
}
}