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  1. #include <bits/stdc++.h>
  2. #define fast ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
  3. #define ll long long
  4. #define ld long double
  5. #define pb push_back
  6. using namespace std;
  7. vector<vector<int>>v;
  8. map<pair<int,int>,int>cost;
  9. bool vis[(int)1e5+5];
  10. map<int,int>source;
  11. int a,b;
  12. bool o=0;
  13. void dfs1(int node,int x)
  14. {
  15.     vis[node]=1;
  16.     for(auto child:v[node])
  17.     {
  18.         if(!vis[child])
  19.         {
  20.             if(child!=b) // not reaching dest from source
  21.             {
  22.                 source[x^cost[{node,child}]]=1;
  23.                 dfs1(child,x^cost[{node,child}]);
  24.             }
  25.         }
  26.     }
  27. }
  28. void dfs2(int node,int x)
  29. {
  30.     vis[node]=1;
  31.      for(auto child:v[node])
  32.     {
  33.         if(!vis[child])
  34.         {
  35.                 if(source[x^cost[{node,child}]]|| (x^cost[{node,child}])==0)
  36.                    o=1;
  37.                 dfs2(child,x^cost[{node,child}]);
  38.         }
  39.     }
  40. }
  41. int main()
  42. {fast
  43. int t;
  44. cin>>t;
  45. while(t--)
  46. {
  47.   int n;
  48.   cin>>n>>a>>b;
  49.   v.clear();
  50.   v.resize(n+1);
  51.   source.clear();
  52.   cost.clear();
  53.   o=0;
  54.   for(int i=1;i<=n;i++) vis[i]=0;
  55.   int x,y,z;
  56.   for(int i=0;i<n-1;i++)
  57.   {
  58.       cin>>x>>y>>z;
  59.       v[x].pb(y);
  60.       v[y].pb(x);
  61.       cost[{x,y}]=z;
  62.       cost[{y,x}]=z;
  63.   }
  64. dfs1(a,0); //go from source
  65. for(int i=1;i<=n;i++) vis[i]=0;
  66. dfs2(b,0) ;//go from dest
  67. (o)?cout<<"YES\n":cout<<"NO\n";
  68. }
  69. return 0;
  70. }
Runtime error #stdin #stdout #stderr 0.01s 5504KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
https://ideone.com/0L9wVj
language:
C++ (gcc 8.3)
created:
2 years ago
visibility:
secret

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