"content":"<p>A <strong>good meal</strong> is a meal that contains <strong>exactly two different food items</strong> with a sum of deliciousness equal to a power of two.</p>\n\n<p>You can pick <strong>any</strong> two different foods to make a good meal.</p>\n\n<p>Given an array of integers <code>deliciousness</code> where <code>deliciousness[i]</code> is the deliciousness of the <code>i<sup>th</sup></code> item of food, return <em>the number of different <strong>good meals</strong> you can make from this list modulo</em> <code>10<sup>9</sup> + 7</code>.</p>\n\n<p>Note that items with different indices are considered different even if they have the same deliciousness value.</p>\n\n<p> </p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> deliciousness = [1,3,5,7,9]\n<strong>Output:</strong> 4\n<strong>Explanation: </strong>The good meals are (1,3), (1,7), (3,5) and, (7,9).\nTheir respective sums are 4, 8, 8, and 16, all of which are powers of 2.\n</pre>\n\n<p><strong>Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> deliciousness = [1,1,1,3,3,3,7]\n<strong>Output:</strong> 15\n<strong>Explanation: </strong>The good meals are (1,1) with 3 ways, (1,3) with 9 ways, and (1,7) with 3 ways.</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 <= deliciousness.length <= 10<sup>5</sup></code></li>\n\t<li><code>0 <= deliciousness[i] <= 2<sup>20</sup></code></li>\n</ul>\n",
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"similarQuestions":"[{\"title\": \"Two Sum\", \"titleSlug\": \"two-sum\", \"difficulty\": \"Easy\", \"translatedTitle\": null}, {\"title\": \"Max Number of K-Sum Pairs\", \"titleSlug\": \"max-number-of-k-sum-pairs\", \"difficulty\": \"Medium\", \"translatedTitle\": null}, {\"title\": \"Find All Possible Recipes from Given Supplies\", \"titleSlug\": \"find-all-possible-recipes-from-given-supplies\", \"difficulty\": \"Medium\", \"translatedTitle\": null}]",
"Note that the number of powers of 2 is at most 21 so this turns the problem to a classic find the number of pairs that sum to a certain value but for 21 values",
"You need to use something fasters than the NlogN approach since there is already the log of iterating over the powers so one idea is two pointers"
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