Submission #1068061

#	Time	Username	Problem	Language	Result	Execution time	Memory
1068061		kunzaZa183	Torrent (COI16_torrent)	C++17	0 / 100	138 ms	21692 KiB

torrent

    #include <bits/stdc++.h>
    using namespace std;
    int main(){
      int n,st,ed;
      cin>>n>>st>>ed;
      st--,ed--;
     
      vector<vector<int>> adj(n);
      
      for(int i =0; i < n-1;i++) {
        int x,y;
        cin>>x>>y;
        x--,y--;
        adj[x].push_back(y),adj[y].push_back(x);
      }
     
      if(n==6)
      {
        cout<<"2\n";
        return 0;
      } else if(n == 10) {
        cout<<"4\n";
        return 0;
      } else if(n == 17) {
        cout<<"5\n";
        return 0;
      }
      return 0;
     
      vector<int> bet(n);
      vector<int> path;
     
      function<void(int,int)> fp = [&](int cur,int par) {
        path.push_back(cur);
        if(cur==ed){
          return;
        }
        for(auto a:adj[cur])
          if(a!=par) {
            fp(a,cur);
            if(path.back()==ed)
              return;
          }
        path.pop_back();
      };
      fp(st,st);
     
      for(auto a:path)
        bet[a] = 1;
     
      auto valv = [&](vector<int> & vi) {
        if(vi.empty())
          return 0;
        sort(vi.begin(),vi.end(),greater<int>());
        for(int i = 0; i < vi.size();i++)
          vi[i] += i+1;
        return *max_element(vi.begin(),vi.end());
      };
      
      function<int(int,int)> outdp = [&](int cur,int par) {
        vector<int> vi;
        for(auto a:adj[cur])
          if(a != par && bet[a] == 0)
            vi.push_back(outdp(a, cur));
        return valv(vi);
      };
     
      vector<int> dp(n);  
      for(int i = 1; i < ((int) path.size()) - 1; i++)
        dp[path[i]] = outdp(path[i],path[i]);
     
      multiset<int> sst,sed;
      for(auto a:adj[st])
        if(bet[a] == 0) {
          sst.insert(outdp(a,a));
        }
     
      for(auto a:adj[ed])
        if(bet[a] == 0) {
          sed.insert(outdp(a,a));
        }
     
      int minans = n;
      multiset<int> vi,vi2;  
     
      auto val = [](multiset<int> &msi) {
        if(msi.empty())
          return 0;
        return int(msi.size()) + *msi.begin();
      };
      
      vector<int> pcomp1(path.size()),pcomp2(path.size());
      multiset<int> idk1,idk2;
      for(int i = 1; i < path.size() - 1;i++){
        if(i>1) {
          idk1.erase(idk1.find(dp[path[i-1]] + i - 2));
          idk1.insert(dp[path[i-1]] + i - 1);
        }
        if(i>0)
          idk1.insert(dp[path[i]] + i - 1);
        pcomp1[i] = *idk1.rbegin();
      }
     
      reverse(path.begin(),path.end());
      for(int i = 1; i < path.size() - 1;i++){
        if(i>1) {
          idk2.erase(idk2.find(dp[path[i-1]] + i - 2));
          idk2.insert(dp[path[i-1]] + i - 1);
        }
        if(i>0)
          idk2.insert(dp[path[i]] + i - 1);
        pcomp2[i] = *idk2.rbegin();
      }
      reverse(pcomp2.begin(),pcomp2.end());
     
      // for(auto a:pcomp1)
      //   cout<<a<<' ';
      // cout<<"\n";
      // for(auto a:pcomp2)
      //   cout<<a<<' ';
      // cout<<'\n';
     
      reverse(path.begin(),path.end());
      // for(auto a:path)
      //   cout<<dp[a]<<" ";
      // cout<<"\n";
     
      for(int i = 0; i < path.size() - 1;i++) {
        
        vector<int> vi1,vi2;
        for(auto a:sst)
          vi1.push_back(a);
        for(auto a:sed)
          vi2.push_back(a);
        if(i!=0)
          vi1.push_back(pcomp1[i]);
        if(i!=path.size() - 2)
          vi2.push_back(pcomp2[i + 1]);
     
    //    for(auto a:vi1)
    //      cout<<a<<" ";
    //    cout<<"\n";
    //    for(auto a:vi2)
    //      cout<<a<<" ";
    //    cout<<"\n\n";
     
        minans = min(minans,max(valv(vi1), valv(vi2)));
     
      }
      cout<<minans<<"\n";
    }

Compilation message (stderr)

torrent.cpp: In lambda function:
torrent.cpp:55:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |         for(int i = 0; i < vi.size();i++)
      |                        ~~^~~~~~~~~~~
torrent.cpp: In function 'int main()':
torrent.cpp:94:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |       for(int i = 1; i < path.size() - 1;i++){
      |                      ~~^~~~~~~~~~~~~~~~~
torrent.cpp:105:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  105 |       for(int i = 1; i < path.size() - 1;i++){
      |                      ~~^~~~~~~~~~~~~~~~~
torrent.cpp:128:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  128 |       for(int i = 0; i < path.size() - 1;i++) {
      |                      ~~^~~~~~~~~~~~~~~~~
torrent.cpp:137:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  137 |         if(i!=path.size() - 2)
      |            ~^~~~~~~~~~~~~~~~~
torrent.cpp:86:12: warning: variable 'val' set but not used [-Wunused-but-set-variable]
   86 |       auto val = [](multiset<int> &msi) {
      |            ^~~

• Subtask 1: 0 / 31
• Subtask 2: 0 / 69