package MonteCarlo;

import java.util.Scanner;

/**
 * 
 */

/**
 * @author Administrator
 *
 */
public class MonteCarlo{

	/**
	 * @param args
	 */
	MonteCarlo(){
		
	}
	
	public static void coinFlipping(int l, int m, int n, double p){
		double totalFlips = 0;
		for(int instance = 1; instance <= 1000000; instance ++){ //simulate the process 1 million time
			int flips = 0;
			int man[] = new int[4];
			man[1] = l;
			man[2] = m;
			man[3] = n;
			while (man[1] > 0 && man[2] > 0 && man[3] > 0){ //toss until one man is ruined
				int  []flip = new int[4];
				//toss
				for(int i = 1; i <=3; i++){
					if (Math.random() < p) flip[i] = 1; 
					else flip[i] = 0; 
				}//for 
				double sum = flip[1] + flip[2] + flip[3];
				if(sum == 1 || sum == 2){ //someone wins
					if(sum == 1){
						for(int i = 1; i <=3; i++){
							if(flip[i] == 0)flip[i] = -1;
							else flip[i] = 2;
						}
					}//fi
					else{
						for(int i = 1; i <=3; i++){
							if(flip[i] == 0)flip[i] = 2;
							else flip[i] = -1;
						}
					}//else
					for(int i = 1; i <=3; i++){
						man[i] += flip[i];
					}
				}//fi 
				flips++;
			}//while
			totalFlips += flips;
		}//for 
		System.out.println("Coin Flipping Game, number of tosses: " + totalFlips / 1000000);
	}
	
	
	public static void missingSenators(){
		Scanner input = new Scanner(System.in);
		System.out.println("Input A: ");
		int A = input.nextInt();
		System.out.println("Input M: ");
		int M = input.nextInt();
		double defeats = 0;
		for(int instance = 1; instance <= 1000000; instance ++){//simulate the experiment process 1 million times
			int votes[] = new int [101];
			for(int i = 1; i <= A; i++)votes[i] = -1; //A senators vote against the bill
			for(int i = A + 1; i <= 100; i++)votes[i] = 1; //100-A senators vote for the bill
			for(int i = 1; i <= M; i++){ //M senators are absent
				int go = 1;
				while(go == 1){//randomly choose one senator to be  absent
					int j = (int) Math.floor(Math.random() * 100) + 1; //[1,100]
					if(votes[j] != 0){ //j can be set as  absent
						votes[j] = 0; //mark her as absent
						go = 0;
					}
				}//while
			}//for
			int sum = 0;
			for(int i = 1; i <= 100; i++) sum += votes[i];
			if(sum <0) defeats ++; //defeat
		}//for
		System.out.println("Missing Senators, probability of being defeated: " + defeats / 1000000);
	}
	
	public static void waitingBuses(){
		Scanner input = new Scanner(System.in);
		System.out.println("Input number of bus lines: ");
		int n = input.nextInt();
		double totalWaitingTime = 0;
		for(int instance = 1; instance <= 1000000; instance ++){//simulate the experiment process 1 million times
			double [] busArrivals = new double [n+1];
			busArrivals[1] = 0; //bus line 1 arrival
			for(int j = 2; j <= n; j++)busArrivals[j] = Math.random();//bus line 2 to n arrival
			double visitorArrival = Math.random(); //visitor arrival
			java.util.Arrays.sort(busArrivals); //sort in ascending order
			
			double waitingtime = 0;
			if(visitorArrival > busArrivals[n]) waitingtime = 1 - visitorArrival; //visitor arrives after bus line n
			else{
				int j = 2;
				while(j <= n){
					if(visitorArrival < busArrivals[j]){//visitor arrives between bus j-1 and bus j
						waitingtime = busArrivals[j] - visitorArrival;
						break; //jump out of the while loop
					}
					j ++; 
				}//while
			}//else
			totalWaitingTime += waitingtime;
		}
		System.out.println("Average waiting time: " + totalWaitingTime / 1000000);
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//MonteCarlo.coinFlipping(1,1,1,0.5);
		//missingSenators();
		waitingBuses();
	}

}