0797.cpp

class Solution {
  public:
    vector<vector<int>> allPathsSourceTarget(vector<vector<int>> &graph) {
        int n = graph.size();

        vector<vector<int>> res;
        unordered_set<int> visited;
        vector<int> path;
        stack<int> st;

        st.push(0);
        while (!st.empty()) {
            int root = st.top();
            st.pop();

            if (root == n - 1) {
                path.push_back(root);
                res.push_back(path);
                path.pop_back();
                continue;
            }

            if (visited.count(root)) {
                visited.erase(root);
                path.pop_back();
                continue;
            }

            path.push_back(root);
            visited.insert(root);
            st.push(root);

            for (int n : graph[root])
                if (!visited.count(n)) st.push(n);
        }

        return res;
    }
};