Activate Fountain - Company-specific OAs / Twitter OA

There is a one-dimensional garden of length n - 1 meters. Every 1 meter there is a sprinkler, and each sprinkler has a different covering range. The sprinklers are labelled 0 ~ n - 1, indicating that the sprinklers are 0 ~ n - 1 meters away from the start of the fountain. The ith sprinkler covers r[i] meters of land, meaning that everywhere from i - r[i] meters to i + r[i] meters (inclusive) will be covered by the sprinkler.

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