797. All Paths From Source to Target

class Solution {
    public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
        List<List<Integer>> result = new LinkedList<>();
        recursion(graph, 0, new LinkedList<Integer>(), result);
        return result;
    }

    private void recursion(int[][] graph, int i, List<Integer> list, List<List<Integer>> result){
        list.add(i);
        if(i==graph.length-1){
            // make a copy of all elements in list, 
            // and add it to a new list
            List<Integer> ans = new LinkedList(list);
            result.add(ans);
        }

        // i will be always valid
        int[] children = graph[i];
        for(int child: children){
            recursion(graph, child, list, result);
        }
        // backtrack
        list.remove(list.size()-1);
    }
}