LeetCode 834 Sum of Distances in Tree - Problem Statement

Given a tree, for each node $i$, compute the sum of distances from $i$ to all other nodes. Distance = number of edges. Example: Tree with edges $[[0,1],[0,2],[2,3],[2,4],[2,5]]$.

Answer: $[8,12,6,10,10,10]$. Node $2$ has the smallest sum ($6$) because it's most central. With naive BFS from each node, you'd get $O(n^2)$. Let's solve it in $O(n)$ with rerooting.