func_code_string: #include <bits/stdc++.h>   using namespace std;   char comp[200005];   vector<pair<int, int> > edge[200005];   vector<int> father[200005];   vector<string> ans;   int dis[200005], n, k;   queue<pair<int, int> > q;   void dfs(int u) {     if (ans.size() >= k) return;     if (u == n + 1) {       ans.push_back(comp + 1);       return;     }     for (int i = 0; i < father[u].size(); i++) {       comp[father[u][i]] =  1 ;       dfs(u + 1);       comp[father[u][i]] =  0 ;     }   }   int main() {     char a[10];     int m;     cin >> n >> m >> k;     for (int i = 1; i <= m; i++) {       int u, v;       scanf( %d %d , &u, &v);       edge[u].push_back(make_pair(v, i));       edge[v].push_back(make_pair(u, i));     }     memset(dis, -1, sizeof(dis));     for (int i = 1; i <= m; i++) comp[i] =  0 ;     q.push(make_pair(1, 0));     dis[1] = 0;     while (!q.empty()) {       pair<int, int> pa = q.front();       q.pop();       int u = pa.first, d = pa.second;       for (int i = 0; i < edge[u].size(); i++) {         int v = edge[u][i].first;         if (dis[v] == -1) {           dis[v] = d + 1;           q.push(make_pair(v, d + 1));         }       }     }     for (int i = 2; i <= n; i++) {       for (int j = 0; j < edge[i].size(); j++) {         if (dis[i] == dis[edge[i][j].first] + 1)           father[i].push_back(edge[i][j].second);       }     }     dfs(2);     if (ans.size() >= k) {       cout << k << endl;       for (int i = 0; i < k; i++) cout << ans[i] << endl;     } else {       cout << ans.size() << endl;       for (int i = 0; i < ans.size(); i++) cout << ans[i] << endl;     }     return 0;   }   