MountainRunner.java (2014 FRQ part 2)

import java.util.Arrays;

class Mountain {
    public static boolean isIncreasing(int[] array, int stop) {
        for (int i = 0; i < stop; i++)
            if (array[i] > array[i + 1])
                return false;
        return true;
    }

    public static boolean isDecreasing(int[] array, int start) {
        for (int j = start; j<array.length - 1; j++)
            if (array[j] < array[j+1])
                return false;
        return true;
    }

    public static int getPeakIndex(int[] array) {
        for (int i = 1; i < array.length - 1; i++)
            if (array[i] > array[i - 1] && array[i] > array[i + 1])
                return i;
        return -1;
    }

    public static boolean isMountain(int[] array) {
        int index = getPeakIndex(array);
        return index != -1 && isIncreasing(array, index - 1) && isDecreasing(array, index + 1);
    }
}

public class MountainRunner {
    public static void main(String[] args) {
        String output = "";
        int[][] arr = {{1, 2, 3, 2, 1}, {1, 2, 1, 2, 1}, {1, 2, 3, 1, 5}, {1, 4, 2, 1, 0}, {9, 3, 5, 7, 5}, {3, 2, 1}};



        for (int[] a : arr)
            System.out.println((Mountain.getPeakIndex(a) != -1 ? "Peak is " + Mountain.getPeakIndex(a) + " - " : "No peak - ")
                    + Arrays.toString(a) + " is a mountain :: " + Mountain.isMountain(a));
    }
}