1897: Rails

Problem Description

Solution in Java

    /**
     * @author Teerapat Phokhonwong
     * @Onlinejudge: URI Online Judge
     * @Problem: 1062 Rails
     * @Link: https://www.urionlinejudge.com.br/judge/en/problems/view/1062
     * @Timelimit: 1 sec
     * @Status: Accepted 19/11/2015 - 07:14:15 Runtime:0.112s
     * @Solution: 
     */
    package  URI.Accepted.DATA_STRUCTURES_AND_LIBRARIES.sourcecode;

    import java.io.BufferedOutputStream;
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import java.util.StringTokenizer;

    public class P1062_Rails {

        static int[] station;
        static int top;

        public static void main(String[] args) throws IOException {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            OutputStream out = new BufferedOutputStream(System.out);
            int n;
            while ((n = Integer.parseInt(br.readLine())) != 0) {
                String line = "";
                while (!(line = br.readLine()).equals("0")) {
                    station = new int[n];
                    top = -1;
                    int[] a = new int[n];
                    int head = n;
                    StringTokenizer stk = new StringTokenizer(line);
                    for (int i = 0; stk.hasMoreTokens(); i++) {
                        a[i] = Integer.parseInt(stk.nextToken());
                    }
                    int j = 0;
                    for (int i = n - 1; i >= 0; i--) {
                        if (a[i] == head) {
                            head--;
                            j++;
                        } else {
                            push(a[i]);
                        }

                        while (!stationIsEmpty() && station[top] == head) {
                            pop();
                            j++;
                            head--;
                        }
                    }

                    if (stationIsEmpty()) {
                        out.write("Yes\n".getBytes());
                    } else {
                        out.write("No\n".getBytes());
                    }

                }
                out.write("\n".getBytes());
            }
            out.flush();
        }

        static void push(int coach) {
            top++;
            station[top] = coach;
        }

        static int pop() {
            int pop = station[top];
            top--;
            return pop;
        }

        static boolean stationIsEmpty() {
            return top == -1;
        }

    }