#P12177. Index Difference and XOR Sum
Index Difference and XOR Sum
Index Difference and XOR Sum
You are given a sequence of n integers, \(a_1, a_2, \ldots, a_n\). Your task is to compute the following sum:
\[ \sum_{i=1}^{n} \sum_{j=i+1}^{n} \Bigl( (a_i \oplus a_j) \times (j-i)\Bigr), \]
Here, \(\oplus\) denotes the bitwise XOR operation. In other words, for every pair \((i, j)\) with \(1 \le i < j \le n\), you need to calculate \((a_i \oplus a_j) \times (j-i)\) and then output the sum of all these values.
inputFormat
The first line contains an integer \(n\) representing the number of elements.
The second line contains \(n\) space-separated integers \(a_1, a_2, \ldots, a_n\).
outputFormat
Output a single integer which is the computed sum:
\[ \sum_{i=1}^{n} \sum_{j=i+1}^{n} \Bigl( (a_i \oplus a_j) \times (j-i)\Bigr) \]
sample
2
1 2
3