km98. 所有可达路径（邻接矩阵+邻接表）

邻接矩阵

#include <cstdio>
#include <vector>
#include <iostream>

static std::vector<std::vector<int>> result;
static std::vector<int> path;

void dfs(std::vector<std::vector<int>>& graph, int x, int n) {
    if(x == n) {
        result.push_back(path);
        return;
    }
    for(int i = 1; i <= n; i++) {
        if(graph[x][i]) {
            path.push_back(i);
            dfs(graph, i, n);
            path.pop_back();
        }
    }
}

int main() {
    int n, m;
    std::cin >> n >> m;
    std::vector<std::vector<int>> graph(n + 1, std::vector<int>(n + 1, 0));
    for(int i = 0; i < m; i++) {
        int a, b;
        std::cin >> a >> b;
        graph[a][b] = 1;
    }
    path.push_back(1);
    dfs(graph, 1, n);
    if(result.size() == 0) std::cout << -1 << std::endl;
    else {
        for(auto p : result) {
            for(int i = 0; i < p.size() - 1; i++) std::cout << p[i] << " ";
            std::cout << p[p.size() - 1] << std::endl;
        }
    }
    
    return 0;
}

邻接表

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

static std::vector<int> path;
static std::vector<std::vector<int>> result;

void dfs(const std::vector<std::list<int>>& graph, int cur, const int n) {
    if(cur == n) {
        result.push_back(path);
        return;
    }
    
    for(auto it = graph[cur].begin(); it != graph[cur].end(); it++) {
        path.push_back(*it);
        dfs(graph, *it, n);
        path.pop_back();
    }
    
}

int main() {
    int n;  // n个节点
    int m;  // m条边
    std::cin >> n >> m;
    std::vector<std::list<int>> graph(n + 1);
    for(int i = 0; i < m; i++) {
        int a, b;
        std::cin >> a >> b;
        graph[a].push_back(b);
    }
    
    path.push_back(1);
    dfs(graph, 1, n);
    
    if(result.size() == 0) std::cout << -1 << std::endl;
    else {
        for(auto p : result) {
            for(int i = 0; i < p.size() - 1; i++) {
                std::cout << p[i] << " ";
            }
            std::cout << p[p.size() - 1] << std::endl;
        }
    }
    
    return 0;
}