public int binarySearch(int[] nums, int target) {
    if (nums == null || nums.length == 0) {
        return -1;
    }

    int start = -1, end = nums.length;
    int mid;
    while (start + 1 < end) {
        // avoid overflow when (end + start)
        mid = start + (end - start) / 2;
        if (nums[mid] < target) {
            start = mid;
        } else {
            end = mid;
        }
    }

    if (end == nums.length || nums[end] != target) {
        return -1;
    } else {
        return end;
    }
}