图论01

98. 所有可达路径

#include <iostream>
#include <list>
#include <vector>

using namespace std;

vector<vector<int>> result;
vector<int> path;

void dfs(vector<list<int>> &graph, int x, int n)
{
    if(x == n)  {result.push_back(path); return;}
     for (int i : graph[x]) { // 找到 x指向的节点
        path.push_back(i); // 遍历到的节点加入到路径中来
        dfs(graph, i, n); // 进入下一层递归
        path.pop_back(); // 回溯，撤销本节点
    }
}

int main()
{
    int n, m, s, t;
    cin >> n >> m;
    vector<list<int>> graph(n + 1);
    while(m--)
    {
        cin >> s >> t;
        graph[s].push_back(t);
    }
    path.push_back(1); // 无论什么路径已经是从0节点出发
    dfs(graph, 1, n);
    if (result.size() == 0) cout << -1 << endl;
    
    for (const vector<int> &pa : result) {
        for (int i = 0; i < pa.size() - 1; i++) {
            cout << pa[i] << " ";
        }
        cout << pa[pa.size() - 1]  << endl;
    }
    return 0;
}