RankCalc.java

public class RankCalc {

	static final int LP_PER = 25;
	static final int XP_PER = 830;
	static int rank, lp, xp, plays, xpEarned;

	public static void main(String[] args) {
		rank = 2;
		xp = plays = xpEarned = 0;
		lp = getMaxLP(rank);

		while(lp >= LP_PER)
			play();

		System.out.println("Final Rank is " + rank);
		System.out.println("Played " + plays + " songs, and earned a total of " + xpEarned + " XP");
		System.out.printf("Assuming 1:40 per song, this would take you %.2f hours.%n", plays * 100.0 / 3600.0);
		System.out.printf("Or %.2f hours, if you use 4X.%n", plays * 25.0 / 3600.0);
	}

	static void play() {
		xp += XP_PER;
		xpEarned += XP_PER;
		lp -= LP_PER;
		plays++;

		while(xp > getXPReq(rank))
			rankUp();
	}

	static void rankUp() {
		xp -= getXPReq(rank);
		rank++;
		lp += getMaxLP(rank);
	}

	static int getXPReq(int rank) {
		return (int) (Math.round(34.45 * rank - 551) * (rank < 100 ? 0.5 : 1));
	}

	static int getMaxLP(int rank) {
		return 25 + (int) Math.floor(Math.min(rank, 300) / 2) + (int) Math.floor(Math.max(rank - 300, 0) / 3);
	}

}