797. All Paths From Source to Target

leetcode.com/problems/all-paths-from-source-to-target/

class Solution {
    
    /*
    - node i direct to nodes in graph[i]
    - find all paths from node 0 to node n-1
    
    //strategy
    1. bfs > q
    2. dfs > st
    
    //process
    1. input
    2. process
    
    mat[i][j] = 1 -> node i -> node j
    
    graph[0] = [1, 2]
    graph[1] = [3]
    graph[2] = [3]
    graph[3] = []
    
    */
    
    int start, end, len;
    boolean[] visit;
    List<List<Integer>> ans = new ArrayList<>();
    
    public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
        len = graph.length;
        start = 0;
        end = len - 1;
        visit = new boolean[len];
            
        dfs(graph, 0, new ArrayList<Integer>());
        return ans;
    }
    
    public void dfs(int[][] graph, int cur, List<Integer> path) {
        // already visit
        if(visit[cur]) {
            return;
        }
        
        visit[cur] = true;
        path.add(cur);
        if(cur == end) {
            ans.add(new ArrayList<Integer>(path));
        }
        //adjacent node
        for(int adj : graph[cur]) {
            if(!visit[adj]) {
                dfs(graph, adj, path);
            }
        }
        visit[cur] = false;
        path.remove(path.size()-1);
    }
}