Constant Space Complexity O(1) describes algorithms that require a fixed amount of memory, regardless of the input size. This means that no matter how large the input gets, the algorithm only uses a constant, limited amount of additional memory.

Constant space complexity is common in algorithms that use a fixed number of variables or operate in-place on the input data without needing extra memory for structures like arrays or lists.

Key Characteristics

In an algorithm with O(1) space complexity:

• Memory usage remains constant, regardless of the size of the input.