public static void DoTurn(PlanetWars pw) {
    
    //notice that a PlanetWars object called pw is passed as a parameter which you could use
    //if you want to know what this object does, then read PlanetWars.java

    //create a source planet, if you want to know what this object does, then read Planet.java
		Planet source = null;

    //create a destination planet
		Planet dest = null;

    //(1) send ships from the more powerfull planet
    	int maxShips = 0;
        for (Planet p : pw.MyPlanets()){
            if (p.NumShips() > maxShips){
                maxShips = p.NumShips();
                source = p;
            }
        }
        if (source==null){
            source = pw.MyPlanets().get(0);
        }

    //(2) send ships to the biggest ennemy planet
        int maxGR = 0;
        for (Planet p : pw.EnemyPlanets()){
            if (p.GrowthRate()>maxGR && Helper.WillCapture(source,p)){  // && Helper.WillCapture(source,p)
                dest = p;
                maxGR = p.GrowthRate();
            }
        }
        if (dest == null) {
            dest = source;
        }

		//(3) Attack
		if (source != null && dest != null) {
			pw.IssueOrder(source, dest);
		}
	}