graph describes a directed acyclic graph with nodes 0 to n - 1: graph[i] is the list of nodes that i points to. Return every path from node 0 to node n - 1, each as an array of nodes.
- The order of the paths, and which of them comes first, does not matter (the tests sort them)
- There is no cycle, so you do not need a visited set; two different paths may pass through the same node
- Each returned path must be its own array: the arrays must not change after you return them
- If node
n - 1 cannot be reached, return an empty array. A graph with a single node has the one path [0]