#P6034. Modulo XOR Summation
Modulo XOR Summation
Modulo XOR Summation
Given a non-negative integer n
, count the number of ordered pairs of non-negative integers (a, b)
such that:
$$\sum_{a=0}^{n} \sum_{b=a+1}^{n} \left[ a \equiv b \pmod{a \oplus b} \right]$$
That is, count the number of pairs (a, b)
with 0 \leq a < b \leq n
satisfying the condition
where (a \oplus b) denotes the bitwise XOR of a
and b
, and the notation (a \equiv b \pmod{m}) means that (m) divides (b - a)
.
You are to output the count of such ordered pairs.
inputFormat
The input consists of a single integer n
on a single line.
Constraints: 0 \le n \le 10^3
. A brute-force solution is acceptable under these constraints.
outputFormat
Output a single integer representing the number of valid pairs (a, b)
that satisfy the condition.
sample
0
0