package algs44;
import stdlib.*;
/* ***********************************************************************
 *  Compilation:  javac Arbitrage.java
 *  Execution:    java Arbitrage < input.txt
 *  Dependencies: EdgeWeightedDigraph.java DirectedEdge.java
 *                BellmanFordSP.java
 *  Data file:    http://algs4.cs.princeton.edu/44sp/rates.txt
 *
 *  Arbitrage detection.
 *
 *  % more rates.txt
 *  5
 *  USD 1      0.741  0.657  1.061  1.005
 *  EUR 1.349  1      0.888  1.433  1.366
 *  GBP 1.521  1.126  1      1.614  1.538
 *  CHF 0.942  0.698  0.619  1      0.953
 *  CAD 0.995  0.732  0.650  1.049  1
 *
 *  % java Arbitrage < rates.txt
 *  1000.00000 USD =  741.00000 EUR
 *   741.00000 EUR = 1012.20600 CAD
 *  1012.20600 CAD = 1007.14497 USD
 *
 *************************************************************************/

public class Arbitrage {

	public static void main(String[] args) {

		// V currencies
		int V = StdIn.readInt();
		String[] name = new String[V];

		// create complete network
		EdgeWeightedDigraph G = new EdgeWeightedDigraph(V);
		for (int v = 0; v < V; v++) {
			name[v] = StdIn.readString();
			for (int w = 0; w < V; w++) {
				double rate = StdIn.readDouble();
				DirectedEdge e = new DirectedEdge(v, w, -Math.log(rate));
				G.addEdge(e);
			}
		}

		// find negative cycle
		BellmanFordSP spt = new BellmanFordSP(G, 0);
		if (spt.hasNegativeCycle()) {
			double stake = 1000.0;
			for (DirectedEdge e : spt.negativeCycle()) {
				StdOut.format("%10.5f %s ", stake, name[e.from()]);
				stake *= Math.exp(-e.weight());
				StdOut.format("= %10.5f %s\n", stake, name[e.to()]);
			}
		}
		else {
			StdOut.println("No arbitrage opportunity");
		}
	}

}