#include<bits/stdc++.h> using namespace std; vector<int> adj[100005]; bool visited[100005]; void dfs(int node){ for(int i=0;i<adj[node].size();i++){ if(!visited[adj[node][i]]){ visited[adj[node][i]]=true; dfs(adj[node][i]); } } } int main(){ ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); int n,m,x,y; cin >> n >> m; for(int i=1;i<=m;i++){ cin >> x >> y; adj[y].push_back(x); } dfs(1); bool stat=false; for(int i=1;i<=n;i++){ if(visited[i])stat=true; } if(!stat){ visited[1]=true; } for(int i=1;i<=n;i++){ if(visited[i])cout << 1; else cout << 0; } cout << endl; return 0; }

wand.cpp: In function 'void dfs(int)':
wand.cpp:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<adj[node].size();i++){
              ~^~~~~~~~~~~~~~~~~