Topological Sort (Directed Graph Ordering)

Problem: Topological Sort (Directed Graph Ordering) Given a directed graph with n nodes labeled 0..n-1, and a list of directed edges edges, where each edge (u, v) means you must finish/visit u before v. Return any valid topological ordering (an array/list of length n) such that for every edge (u, v), u appears before v. If the graph contains a cycle and no topological ordering exists, return an empty list. Input (common interview conventions) n: number of nodes edges: list of edges, each as two integers u v Output Print the ordering space-separated, or print an empty line/empty array if impossible. Constraints 1 <= n <= 2 * 10^5 0 <= len(edges) <= 2 * 10^5 Example Input: n = 4, edges = [(1,0),(2,0),(3,1),(3,2)] Possible output: 3 1 2 0 (Any valid ordering is acceptable.) Example Input 4 4 1 0 2 0 3 1 3 2 Output 3 1 2 0 （或任意合法拓扑序）