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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long 
  4. #define dbg(x) cout<<#x<<" : "<<x<<endl
  5. #define rep(i,a,b) for(int i=(a);i<=(b);i++)
  6. #define maxm 1000005
  7. #define maxn 100005
  8. #define inf 1000000000000000000
  9. vector<ll> edges[maxm];
  10. ll d[maxn],par[maxn],dau[maxn];
  11. ll n,m,s,t;
  12. vector<ll> res;
  13. void solve(ll destination){
  14.     if(destination==par[destination]){
  15.         res.push_back(destination);
  16.         return;
  17.     }
  18.     res.push_back(destination);
  19.     destination = par[destination];
  20.     solve(destination);
  21. }
  22. void bfs(ll source){
  23.     dau[source]=1;
  24.     d[source]=0;
  25.     queue<ll> q;
  26.     q.push(source);
  27.     while(!q.empty()){
  28.         ll p = q.front();
  29.         q.pop();
  30.         for(auto v: edges[p]){
  31.             if(dau[v]==1) continue;
  32.             dau[v]=1;
  33.             if(d[v]>d[p]+1){
  34.                 par[v]=p;
  35.                 d[v]=d[p]+1;
  36.             }
  37.             q.push(v);
  38.         }
  39.     }
  40. }
  41. int main(){
  42.     // freopen("input.txt","r",stdin);
  43.     // freopen("output.txt","w",stdout);
  44.     cin>>n>>m>>s>>t;
  45.     s--,t--;
  46.     for(ll i=0;i<m;i++){
  47.         ll u,v;
  48.         cin>>u>>v;
  49.         u--,v--;
  50.         edges[u].push_back(v);
  51.     }
  52.     for(ll i=0;i<n;i++) sort(edges[i].begin(),edges[i].end());
  53.     for(ll i=0;i<n;i++) d[i]=inf;
  54.     par[s]=s;
  55.     bfs(s);
  56.     solve(t);
  57.     reverse(res.begin(),res.end());
  58.     for(auto v: res) cout<<v+1<<" ";
  59.     return 0;
  60. }
Success #stdin #stdout 0.01s 29184KB
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https://ideone.com/yRs2vr
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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