XOR - MarisaOJ: Marisa Online Judge

XOR

Time limit: 1000 ms
Memory limit: 256 MB
Given an array $a$ consisting of $n$ non-negative integers. Count the number of pairs $1 \le i, j \le n$ such that $a_i \le (a_i \oplus a_j) \le a_j$. ### Input - The first line contains an integer $n$. - The second line contains $n$ positive integers $a_i$. ### Output - Print a single integer — the number of valid pairs $i,j$. ### Constraints - $1 \le n \le 5 \times 10^5$. - $0 \le a_i < 2^{30}$. ### Example Input: ``` 5 0 1 2 3 4 ``` Output: ``` 6 ```