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g1701_1800.s1711_count_good_meals.readme.md Maven / Gradle / Ivy

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 ith 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