Topological Sort / Dependency Resolution

Coding: Topological Sort / Dependency Resolution Given a directed graph representing dependencies among tasks labeled 0..n-1. Input First line: two integers n m (number of tasks and edges). Next m lines: two integers u v meaning u must be done before v (edge u -> v). Output If a valid ordering exists, print any topological order (space-separated n integers). If the graph contains a cycle, print IMPOSSIBLE. Constraints 1 <= n <= 2e5 0 <= m <= 2e5 Example Input: 4 3 0 1 1 2 0 3 One valid output: 0 1 3 2 Example Input 4 3 0 1 1 2 0 3 Output 0 1 3 2