2013年 模擬地区予選 Problem A: Broken Audio Signal (解法1) [Licence: NYSL Version 0.9982]

Main.java

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    public static void main(final String... args) {
        final Scanner sc = new Scanner(System.in);
        main:
        while (sc.hasNext()) {
            final int n = sc.nextInt();
            if (n == 0)
                return;
            final String[] in = new String[n];
            for (int i = 0; i < n; i++)
                in[i] = sc.next().intern();

            final Set<Integer> set = new HashSet<>();
            for (final String s : in)
                if (s != "x") {
                    final int i = Integer.parseInt(s);
                    set.add(i + 1);
                    set.add(i - 1);
                }
            set.add(Integer.MAX_VALUE);
            set.add(Integer.MIN_VALUE);


            boolean f = false;
            int ans = 0;

            loop:
            for (final int i : set) {
                final int[] is = new int[n];
                for (int j = 0; j < n; j++)
                    if (in[j] == "x")
                        is[j] = i;
                    else
                        is[j] = Integer.parseInt(in[j]);
                for (int j = 1; j < n; j++)
                    if (j % 2 == 0) {
                        if (is[j - 1] <= is[j])
                            continue loop;
                    } else if (is[j - 1] >= is[j])
                        continue loop;
                if (f) {
                    System.out.println("ambiguous");
                    continue main;
                }
                f = true;
                ans = i;
            }
            if (f)
                System.out.println(ans);
            else
                System.out.println("none");
        }
    }
}