解法：

#include<iostream>
#include<vector>
using namespace std;
int arr[100][100];
int n;
int sta, des;
vector<int> path;
vector<vector<int>> res;
void dfs(vector<int> &a,int i) {
	a[i] = 1;
	path.push_back(i);
	if (i == des) {
		res.push_back(path);
		return;
	}
	for (int j = 0; j < n; j++) {
		if (arr[i][j]&&!a[j]) {
			dfs(a,j);
			path.pop_back();
			a[j] = 0;
		}
	}
}
int main() {

	cin >> n;
	vector<int> vis(n, 0);
	cin >> sta >> des;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < n; j++)
			cin >> arr[i][j];
	dfs(vis,sta);
	for (int i = 0; i < res.size(); i++) {
		for (int j = 0; j < res[i].size(); j++) {
			cout << res[i][j];
		}
		cout << endl;
	}
	return 0;
}