COMB09 - Editorial

Problem Link - Fruit Basket in Combinatorics

Problem Statement:

Chef is preparing a fruit basket for Cheffina, he has N varieties of fruits. In particular, he has A_i number of fruits of the i-th varity.
In how many ways he can prepare the fruit basket?
Chef can add no more than A_i number of the i-th fruit in the basket. Chef can prepare an empty fruit basket.

Approach:

  • Understanding the Combinations:
    • For each variety of fruit i, Chef can choose from 0 to A[i] fruits. This gives A[i]+1 options (including choosing none).
    • The total number of ways to prepare the fruit basket is the product of choices for all fruit varieties.
  • Formula:
    • Total Ways = ∏(A[i]+1) from i=1 to N. Here, N is the number of fruit varieties, and A[i] is the number of fruits of the i-th variety.
    • Since the result can be very large, we will take the result modulo 10^9 + 7.

Complexity:

  • Time Complexity: O(N) For traversing the array once.
  • Space Complexity: O(1) No extra space required.