# 1711. Count Good Meals

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 `i​​​​​​th​​​​`​​​​ item of food, return the number of different good meals you can make from this list modulo `109 + 7`.

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:

• `1 <= deliciousness.length <= 105`
• `0 <= deliciousness[i] <= 220`

Medium

Normal

Robinhood