1711 - Count Good Meals.

Medium

A good meal is a meal that contains exactly two different food items with a sum of deliciousness equal to a power of two.

You can pick any two different foods to make a good meal.

Given an array of integers deliciousness where deliciousness[i] is the deliciousness of the <code>i^th</code> item of food, return the number of different good meals you can make from this list modulo <code>10⁹ + 7</code>.

Note that items with different indices are considered different even if they have the same deliciousness value.

Example 1:

Input: deliciousness = 1,3,5,7,9

Output: 4

Explanation: The good meals are (1,3), (1,7), (3,5) and, (7,9). Their respective sums are 4, 8, 8, and 16, all of which are powers of 2.

Example 2:

Input: deliciousness = 1,1,1,3,3,3,7

Output: 15

Explanation: The good meals are (1,1) with 3 ways, (1,3) with 9 ways, and (1,7) with 3 ways.

Constraints:

• <code>1 <= deliciousness.length <= 10⁵</code>

• <code>0 <= deliciousnessi<= 2²⁰</code>