How to find out if a number exist in billions of numbers?

BitMap

A bitmap is a data structure that stores a collection of bits, each representing a binary digit (0 or 1). It is used to store a large collection of binary values efficiently. In this case, we can use a bitmap to store a large collection of numbers and check if a given number exists in the collection.

1. Create a bitmap of size 1 billion (1,000,000,000).
2. For each number in the billions of numbers, set the corresponding bit in the bitmap to 1.
3. To check if a given number exists in the billions of numbers, simply check the corresponding bit in the bitmap. If the bit is 1, the number exists in the billions of numbers. If the bit is 0, the number does not exist in the billions of numbers.