PivotNumber.java

/**
 * Created by linwei on 9/20/16.
 */
public class PivotNumber {
    /* Test case:
        3 4 5 2 (6) 7 8 9 return 6's index 4
        4 2 6 (5) 7 8 9 return 5's index 3
        4 2 6 5 3 9 return -1
     */
    public int get(int[] array) {
        int pivotIndex = 0;
        int max = array[0];
        int i = 1;
        while (i < array.length) {
            // System.out.println("pivotIndex: " + pivotIndex + ", array[" + i + "]: " + array[i] + ", max: " + max);
            if (array[i] > max) {  // of course it's larger than array[pivotIndex]
                max = array[i];  // update the max
                i++;

            } else if (array[i] > array[pivotIndex]) {
                i++;

            } else if (array[i] < array[pivotIndex]) {
                if (i == array.length - 1) {
                    return -1;
                } else {
                    i++;
                    while (i < array.length && array[i] <= max) {
                        i++;
                    }
                    if (i < array.length) {
                        pivotIndex = i;
                    } else {
                        return -1;
                    }
                }
            }
        }
        if (i == array.length) return pivotIndex;
        else return -1;
    }
}