DFA.java

/* *****************************************************************************
 *  Name:              Ada Lovelace
 *  Coursera User ID:  123456
 *  Last modified:     October 16, 1842
 **************************************************************************** */

public class DFA {
    private String[] action;
    private SymbolTable<Character, Integer>[] next;

    public DFA(String filename) {
        In in = new In(filename);
        int n = in.readInt();
        String alphabet = in.readString();
        action = new String[n];
        next = (SymbolTable<Character, Integer>[]) new SymbolTable[n];
        for (int state = 0; state < n; state++) {
            action[state] = in.readString();
            next[state] = new SymbolTable<Character, Integer>();
            for (int i = 0; i < alphabet.length(); i++) {
                next[state].put(alphabet.charAt(i), in.readInt());
            }
        }
    }

    public String simulate(String input) {
        int state = 0;
        for (int i = 0; i < input.length(); i++) {
            state = next[state].get(input.charAt(i));
        }
        return action[state];
    }

    public static void main(String[] args) {
        DFA dfa = new DFA(args[0]);
        while (StdIn.hasNextLine()) {
            String input = StdIn.readLine();
            System.out.println(dfa.simulate(input));
        }
    }
}