mean the running time must be entirely independent of the problem size; rather, it should have a consistent upper bound irrespective of input size. For example, a task that involves swapping the values of and to ensure is classified as constant time, even if the execution time may vary depending on whether the condition is already met. The key is that there exists a constant such that the time taken will never exceed , regardless of the input values.

Constant-time algorithms are especially significant in contexts like cryptography,