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Вопрос 57

Which statements about reduce are true? Select all that apply.

  1. It always returns an array
  2. It always requires an explicit initial value
  3. It combines elements into one accumulated resultПравильный ответ
  4. A supplied initial value starts the accumulatorПравильный ответ

Объяснение

reduce combines elements through an accumulator, and a supplied initial value starts that accumulation. Without one on a nonempty array, the first element becomes the starting accumulator rather than being combined as an ordinary later element immediately.

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