D-24 submission.md

⚡ Question

Given a directed, acyclic graph of N nodes. Find all possible paths from node 0 to node N-1, and return them in any order. The graph is given as follows: the nodes are 0, 1, ..., graph.length - 1. graph[i] is a list of all nodes j for which the edge (i, j) exists.

Example:
Input: [[1,2], [3], [3], []] 
Output: [[0,1,3],[0,2,3]] 
Explanation: The graph looks like this:
0--->1
|    |
v    v
2--->3
There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.
Note:

The number of nodes in the graph will be in the range [2, 15].
You can print different paths in any order, but you should keep the order of nodes inside one path.

🍑 Solution

    class Solution {
        public List<List<Integer>> allPathsSourceTarget(int[][] graph) {

            int target = graph.length - 1;

            List<List<Integer>> allPathsSourceTarget = new ArrayList<>();

            Queue<List<Integer>> q = new LinkedList<>();
            q.add(new ArrayList<>(Arrays.asList(0)));

            while (!q.isEmpty()) {

                List<Integer> path = q.poll();

                int lastNode = path.get(path.size() - 1);

                if (lastNode == target) allPathsSourceTarget.add(new ArrayList<>(path));
                else {
                    int[] neighbors = graph[lastNode];

                    for (int neighbor : neighbors) {
                        List<Integer> list = new ArrayList<>(path);
                        list.add(neighbor);
                        q.offer(list);
                    }
                }
            }
            return allPathsSourceTarget;
        }
    }