Minimum Edge Reversals So Every Node Is Reachable (Avoid Recursion Stack Overflow)

You are given a tree with n nodes labeled 0..n-1, but each undirected edge is assigned a direction, producing n-1 directed edges. edges[i] = [u, v] denotes a directed edge u -> v. For every node r as a starting node, compute the minimum number of edges that must be reversed (turn x -> y into y -> x) so that all nodes become reachable from r by following directed edges. Return an array ans of length n where ans[r] is that minimum for root r. Requirements: Target O(n) or O(n log n) time. Recursive DFS may stack overflow; use iterative DFS/BFS or an explicit stack. Input (stdin): Line 1: integer n Next n-1 lines: two integers u v meaning a directed edge u -> v Output (stdout): One line with n integers ans[0..n-1] Constraints: 2 <= n <= 200000 0 <= u, v < n The underlying undirected graph is a tree Example: Input: 4 0 1 2 0 3 2 Output: 1 2 1 0 Example Input 4 0 1 2 0 3 2 Output 1 2 1 0