图论Day37：深搜基础

深搜三部曲（回溯法）

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

void dfs(图， 当前节点){
    if(终点){
        result.push_back(path);
        return;
    }
    for(遍历相邻节点) {
        path.push_back(节点);
        dfs(图， 节点)；
        path.pop()//回溯
    }
}

98. 可达路径

#include<iostream>
#include<vector>
using namespace std;

vector<vector<int>> result;
vector<int> path;
void dfs(vector<vector<int>> graph, int cur, int N) {
    if(cur == N) {
        result.push_back(path);
        return;
    }
    for(int i = 1; i <= N; i++){
        if(graph[cur][i] == 0){
            continue;
        }
        path.push_back(i);
        dfs(graph, i, N);
        path.pop_back();
    }
}
int main() {
    int N, M;
    cin >> N >> M;

    vector<vector<int>> graph (N + 1, vector<int>(N + 1, 0));
    while(M--){
        int x, y;
        cin >> x >> y;
        graph[x][y] = 1;
    }
    path.push_back(1);
    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;
    }
}