【HDU】5637

Problem Description
A list of n integers are given. For an integer x you can do the following operations:

+ let the binary representation of x be b31b30...b0¯¯¯¯¯¯¯¯¯¯¯¯¯¯, you can flip one of the bits.
+ let y be an integer in the list, you can change x to x⊕y, where ⊕ means bitwise exclusive or operation.

There are several integer pairs (S,T). For each pair, you need to answer the minimum operations needed to change S to T.
 

Input
There are multiple test cases. The first line of input contains an integer T (T≤20), indicating the number of test cases. For each test case:

The first line contains two integer n and m (1≤n≤15,1≤m≤105) -- the number of integers given and the number of queries. The next line contains n integers a1,a2,...,an (1≤ai≤105), separated by a space.

In the next m lines, each contains two integers si and ti (1≤si,ti≤105), denoting a query.
 

Output
For each test cases, output an integer S=(∑i=1mi⋅zi) mod (109+7), where zi is the answer for i-th query.
 

Sample Input
1
3 3
1 2 3
3 4
1 2
3 9
 

Sample Output
10
Hint

$3 \to 4$ (2 operations): $3 \to 7 \to 4$

$1 \to 2$ (1 operation): $1 \oplus 3 = 2$

$3 \to 9$ (2 operations): $3 \to 1 \to 9$
 
 

Source
BestCoder Round #74 (div.2)
 

Recommend
wange2014

题意分析：

给出n个数的序列a，对于一个整数x，有两种操作： 
1.改变x二进制中任一位 
2.将x变为x^a[i]，1<=i<=n 
m次查询，每次查询输入两个整数x和y，问x最少经过多少次操作可以变成y 

记得mod

假设 s^x^y^z^w^...^q=t 是最小操作次数，由于其等价于 0^x^y^z^w^...^q=s^t，

因此只需要根据所给的 n 个数将 1E5 范围内的所有步数求出来存到 res[] 数组中，

最后根据 s、t 的值直接可以得到 res[s^t] 然后进行计算即可。

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