Sum of Sums
Practice
5 (1 votes)
Algorithms
Depth first search
Graphs
Medium
Problem
93% Success 901 Attempts 50 Points 1s Time Limit 256MB Memory 1024 KB Max Code
Given a undirected tree containing N nodes where ith node has value \( a(i) \). Let us define cost of the tree as C, where
\( C = \sum_{i=1}^N f(i) \)
\( f(i)=\sum_j g(j) ;where \hspace{0.25cm} j \hspace{0.25cm} \epsilon \hspace{0.25cm} subtree \hspace{0.25cm} of \hspace{0.25cm} i \)
\( g(j)=\sum_k a(k) ;where \hspace{0.25cm} k \hspace{0.25cm} \epsilon \hspace{0.25cm} subtree \hspace{0.25cm} of \hspace{0.25cm} j \)
Find a root of the tree such that the cost of the tree is minimum.
Input
The first line of input contains N (1 ≤ N ≤ 100,000) - the number of nodes in the tree.The second line contains N integers a1, a2, ..., aN, where ai (1 ≤ ai ≤ \(10^6\)) is the value stored at the ith node.
The next N-1 lines contains two integers u and v, meaning that there is an edge connecting u and v.
Output
Print two integers, the root of the tree such that the cost of tree is minimum and minimum cost. If there are multiple possible values of root, print the minimum one.
Constraints
- \( 1 \leq N \leq 1000, 1 \leq a(i) \leq 10^6 \) in 40% of test cases.
- \( 1 \leq N \leq 10^5, 1 \leq a(i) \leq 10^6 \) in 60% of test cases.
NOTE: The value of C will fit in 64-bit integer.
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