private boolean binarySearch(int[] num, int target, int s, int e) {
		int mid = 0;
		while (s <= e) {
			mid = s + ((e - s) >> 1);
			if (num[mid] == target) {
				return true;
			} else if (num[mid] > target) {
				e = mid - 1;
			} else {
				s = mid + 1;
			}
		}
		return false;
	}