lintcode447- Search in a Big Sorted Array- medium

public class Solution {
    /*
     * @param reader: An instance of ArrayReader.
     * @param target: An integer
     * @return: An integer which is the first index of target.
     */
    public int searchBigSortedArray(ArrayReader reader, int target) {

        final int MAX = 2147483647;
        int start = 0;
        int end = 1;
        int flip = 1;

        while (reader.get(end) < target){
            end += flip;
            flip *= 2;
            if (flip == 2 && reader.get(end) == MAX){
                return -1;
            }
            if (reader.get(end) == MAX){
                flip /= 2;
                end -= flip;
                flip = 1;
            }
        }

        while (start + 1 < end){
            int mid = start + (end - start) / 2;
            if (target < reader.get(mid)){
                end = mid;
            } else if (target == reader.get(mid)){
                end = mid;
            } else {
                start = mid;
            }
        }
        if (target == reader.get(start)){
            return start;
        }
        if (target == reader.get(end)){
            return end;
        }
        return -1;
    }
}