Count Good Meals

A pair is good when its sum is a power of two. Scan the array and maintain counts of values already seen. For current value x, iterate every power of two in the feasible sum range and add count[power - x] to the answer, then increment count[x]. Inserting after querying ensures each unordered pair is counted once, when its later element is seen. Choose the power range from the stated maximum value rather than guessing; typically powers through the next power above twice the maximum suffice. Apply the required modulus during accumulation and use a wide accumulator first. Do not test every earlier element, which is quadratic. With P relevant powers, time is O(nP) and space is O(n); P is small for bounded integer values.