🧠 Before you code — what pattern fits?
There are n cities and n-1 directed roads connections (a tree if undirected). Reorient the minimum number of roads so every city can reach city 0. Return the minimum number of edges changed.
(6, [[0,1],[1,3],[2,3],[4,0],[4,5]]) → 3
🎬 Video explanation · NeetCode
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