import choco.kernel.solver.search.integer.AbstractIntVarSelector;
import choco.kernel.solver.variables.integer.IntDomainVar;
import choco.kernel.solver.variables.AbstractVar;
import choco.kernel.memory.IStateInt;

public class MagicHeuristic extends AbstractIntVarSelector {

    private IntDomainVar[] vars;           // 0/1 decision variables
    private int n;                         // number of decision variables
    private IStateInt[] deg;               // number of vertices adjacent to v[i] in candidate set, reversible
    private int[] col;                     // colouring of v[i] in candidate set
    private ReversibleVector candidateSet; // the uninstantiated variables

    public MagicHeuristic(IntDomainVar[] vars,IStateInt[] deg,int[] col,ReversibleVector candidateSet){
	this.vars = vars; n = vars.length; this.deg = deg;this.col = col; this.candidateSet = candidateSet;
    }

    public IntDomainVar selectIntVar(){
	int maxColour             = Integer.MIN_VALUE;
	int minDeg                = Integer.MAX_VALUE;
	IntDomainVar magicVar     = null;
	int i                     = 0;
	for (int k=0;k<candidateSet.size();k++){
	    i = candidateSet.get(k);
	    if (col[i] > maxColour || col[i] == maxColour && deg[i].get() < minDeg){
		magicVar = vars[i]; 
		maxColour = col[i];
		minDeg = deg[i].get();
	    }	
	}
	return magicVar;
    }
}
//
// select the uninstantiated variable with max colour tie break on min degree
//