org.jgrapht.alg.interfaces.LowestCommonAncestorAlgorithm Maven / Gradle / Ivy
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/*
* (C) Copyright 2018-2023, by Alexandru Valeanu and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.alg.interfaces;
import org.jgrapht.alg.util.*;
import java.util.*;
import java.util.stream.*;
/**
* Algorithm to compute a lowest
* common ancestor in a tree, forest or DAG.
*
* @param vertex the graph vertex type
*
* @author Alexandru Valeanu
*/
public interface LowestCommonAncestorAlgorithm
{
/**
* Return the LCA of a and b
*
* @param a the first element to find LCA for
* @param b the other element to find the LCA for
*
* @return the LCA of a and b, or null if there is no LCA.
*/
V getLCA(V a, V b);
/**
* Return a list of LCAs for a batch of queries
*
* @param queries a list of pairs of vertices
* @return a list L of LCAs where L(i) is the LCA for pair queries(i)
*/
default List getBatchLCA(List> queries)
{
return queries
.stream().map(p -> getLCA(p.getFirst(), p.getSecond())).collect(Collectors.toList());
}
/**
* Return the computed set of LCAs of a and b
*
* @param a the first element to find LCA for
* @param b the other element to find the LCA for
*
* @return the set LCAs of a and b, or empty set if there is no LCA computed.
* @throws UnsupportedOperationException - if the operation is not supported by the implementing
* class
*/
Set getLCASet(V a, V b);
/**
* Return a list of computed sets of LCAs for a batch of queries
*
* @param queries a list of pairs of vertices
* @return a list L of LCAs where L(i) is the computed set of LCAs for pair queries(i)
*/
default List> getBatchLCASet(List> queries)
{
return queries
.stream().map(p -> getLCASet(p.getFirst(), p.getSecond())).collect(Collectors.toList());
}
}