package util.graph;

import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.Set;

public class DynDjikstra {
    public static State FindShortest(Node start, Node target) {
        PriorityQueue<Node> openSet = new PriorityQueue<>();
        Set<Node> closedSet = new HashSet<>();
        openSet.add(start);
        while (!openSet.isEmpty()) {
            Node current = openSet.poll();
            for (Edge edge : current.edges) {
                Node end = edge.target;
                if (closedSet.contains(end)) {
                    continue;
                }
                State newState = edge.travel(current.last);
                //if (end.equals(target)) {
                    //return newState;
                //}
                if (openSet.contains(end)) {
                    if (end.last.compareTo(newState)>0) {
                        end.last = newState;
                    }
                } else {
                    openSet.add(end);
                    end.last = newState;
                }
            }
            closedSet.add(current);
            if (closedSet.contains(target)) {
                return target.last;
            }
        }

        return target.last;
    }
}

package jp.funnything.competition.util;

import java.util.Iterator;

/**
 * Do NOT change the element in iteration
 */
public class Combination implements Iterable< int[] > , Iterator< int[] > {
    private final int _n;
    private final int _k;
    private int[] _data;

    public Combination( final int n , final int k ) {
        if ( k < 0 || k > n ) {
            throw new IllegalArgumentException();
        }

        _n = n;
        _k = k;
    }

    @Override
    public boolean hasNext() {
        return _data == null || _data.length > 0 && _data[ 0 ] < _n - _k;
    }

    @Override
    public Iterator< int[] > iterator() {
        return this;
    }

    @Override
    public int[] next() {
        if ( _data == null ) {
            _data = new int[ _k ];
            for ( int index = 0 ; index < _k ; index++ ) {
                _data[ index ] = index;
            }
        } else {
            int i = 0;

            while ( i < _k - 1 && _data[ i + 1 ] == _data[ i ] + 1 ) {
                _data[ i ] = i++;
            }

            _data[ i ]++;
        }

        return _data;
    }

    @Override
    public void remove() {
    }
}
