Hard Accuracy: 43.84%
Submissions: 10124 Points: 8
We define f (X, Y) as number of different corresponding bits in binary representation of X and Y. For example, f (2, 7) = 2, since binary representation of 2 and 7 are 010 and 111, respectively. The first and the third bit differ, so f (2, 7) = 2.
You are given an array A of N integers, A1, A2 ,…, AN. Find sum of f(Ai, Aj) for all ordered pairs (i, j) such that 1 ≤ i, j ≤ N. Return the answer modulo 109+7.
You do not need to read input or print anything. Your task is to complete the function countBits() which takes the value N and the array A as input parameters and returns the desired count modulo 109+7.
Expected Time Complexity: O(N * log2(Max(Ai))) Expected Auxiliary Space: O(1)