A10746 | Arpa’s obvious problem and Mehrdad’s terrible solution
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内存限制256MB
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题目描述
There are some beautiful girls in Arpa’s land as mentioned before.
Once Arpa came up with an obvious problem:
Given an array and a number $x$ , count the number of pairs of indices $i,j$ ( $1<=i<j<=n$ ) such that , where  is bitwise xor operation (see notes for explanation).
Immediately, Mehrdad discovered a terrible solution that nobody trusted. Now Arpa needs your help to implement the solution to that problem.
Once Arpa came up with an obvious problem:
Given an array and a number $x$ , count the number of pairs of indices $i,j$ ( $1<=i<j<=n$ ) such that , where  is bitwise xor operation (see notes for explanation).
Immediately, Mehrdad discovered a terrible solution that nobody trusted. Now Arpa needs your help to implement the solution to that problem.
输入格式
First line contains two integers $n$ and $x$ ( $1<=n<=10^{5},0<=x<=10^{5}$ ) — the number of elements in the array and the integer $x$ .
Second line contains $n$ integers $a_{1},a_{2},...,a_{n}$ ( $1<=a_{i}<=10^{5}$ ) — the elements of the array.
Second line contains $n$ integers $a_{1},a_{2},...,a_{n}$ ( $1<=a_{i}<=10^{5}$ ) — the elements of the array.
输出格式
Print a single integer: the answer to the problem.
输入输出样例
输入 #1
2 3 1 2
输出 #1
1
输入 #2
6 1 5 1 2 3 4 1
输出 #2
2
In the first sample there is only one pair of $i=1$ and $j=2$ .  so the answer is $1$ .
In the second sample the only two pairs are $i=3$ , $j=4$ (since ) and $i=1$ , $j=5$ (since ).
A bitwise xor takes two bit integers of equal length and performs the logical xor operation on each pair of corresponding bits. The result in each position is $1$ if only the first bit is $1$ or only the second bit is $1$ , but will be $0$ if both are $0$ or both are $1$ . You can read more about bitwise xor operation here: [https://en.wikipedia.org/wiki/Bitwise\_operation#XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR).
In the second sample the only two pairs are $i=3$ , $j=4$ (since ) and $i=1$ , $j=5$ (since ).
A bitwise xor takes two bit integers of equal length and performs the logical xor operation on each pair of corresponding bits. The result in each position is $1$ if only the first bit is $1$ or only the second bit is $1$ , but will be $0$ if both are $0$ or both are $1$ . You can read more about bitwise xor operation here: [https://en.wikipedia.org/wiki/Bitwise\_operation#XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR).
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评测结果：Accepted