26 Algorithms library [algorithms]

Parallel algorithms are algorithm overloads.

Each parallel algorithm overload has an additional function parameter P of type T&& as the first function parameter, where T is the execution policy template parameter.

Unless otherwise specified, the semantics of calling a parallel algorithm overload are identical to calling the corresponding algorithm overload without the parameter P, using all but the first argument.

Unless otherwise specified, the complexity requirements of a parallel algorithm overload are relaxed from the complexity requirements of the corresponding overload without the parameter P as follows: when the guarantee says “at most expr” or “exactly expr” and does not specify the number of assignments or swaps, and expr is not already expressed with $O\left(\right)$ notation, the complexity of the algorithm shall be $O\left(\text{expr}\right)$.

A parallel algorithm with a template parameter named ExecutionPolicy shall not participate in overload resolution unless that template parameter satisfies execution-policy.