Operations on a tree
Practice
4.2 (6 votes)
Algorithms
Basics of greedy algorithms
C++
Greedy algorithms
Problem
74% Success 878 Attempts 50 Points 1s Time Limit 256MB Memory 1024 KB Max Code

You are given an undirected tree $$G$$ with $$N$$ nodes. You are also given an array $$A$$ of $$N$$ integer elements where $$A[i]$$ represents the value assigned to node $$i$$ and an integer $$K$$.

You can apply the given operation on the tree at most once:

  • Select a node $$x$$ in the tree and consider it as the root of the tree.
  • Select a node $$y$$ in the tree and update the value of each node in the subtree of $$y$$ by taking its XOR with $$K$$. That is, for each node $$u$$ in the subtree of node $$y$$, set $$A[u] = A[u] XOR K$$.

Find the maximum sum of values of nodes that are available in the tree, after the above operation is used optimally.

Note

  • Assume 1-based indexing.
  • XOR represents the bitwise XOR operator. 

Input format

  • The first line contains a single integer $$T$$ that denotes the number of test cases.
  • For each test case:
    • The first line contains an integer $$N$$.
    • The second line contains an integer $$K$$.
    • The third line contains $$N$$ space-separated integers denoting array $$A$$.
    • Next $$N - 1$$ lines contain two space-separated integers denoting an edge between node $$u$$ and $$v$$.

Output format

For each test case, print the maximum possible sum of values of nodes present in the tree. Print the output for each test case in a new line.

Constraints

\(1 \le T \le 10 \\ 1 \le N \le 10^5 \\ 0 \le A[i] \le 10^9 \\ 0 \le K \le 10^9 \)

 

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