For example, if we have seen an element '2' in the array, we can assign Array[1] = -1 * Array[1] which will tell us that element 2 is seen in the array.
ຕົວຢ່າງ: ຖ້າພວກເຮົາໄດ້ເຫັນອົງປະກອບ '2' ໃນອາເລ, ພວກເຮົາສາມາດ ກໍາ ນົດ Array [1] = -1 * Array [1] ເຊິ່ງຈະບອກພວກເຮົາວ່າອົງປະກອບ 2 ແມ່ນເຫັນຢູ່ໃນ array.