尝试将广度优先搜索方法编写到图中时出现分段错误

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

void bfs(vector<vector<int>>& graph, int start) {
    int n = graph.size();
    vector<bool> visited(n, false);
    queue<int> q;

    q.push(start);
    visited[start] = true;

    while (!q.empty()) {
        int node = q.front();
        q.pop();
        cout << node << " ";

        for (int neighbor : graph[node]) {
            if (!visited[neighbor]) {
                q.push(neighbor);
                visited[neighbor] = true;
            }
        }
    }
}

int main() {
    vector<vector<int>> graph = {
        {1, 2},
        {0, 2, 3},
        {0, 1, 3},
        {1, 2}
    };

    bfs(graph, 0);

    return 0;
}