Submission #479404

#	Time	Username	Problem	Language	Result	Execution time	Memory
479404		DDTerziev04	Graph (BOI20_graph)	C++14	100 / 100	298 ms	20292 KiB

Graph

#include<iostream>
#include<vector>
using namespace std;

const int MAXN=1e5;
const double INF=1e9;

vector<pair<int, int> > adj[MAXN];
vector<int> seg;
double val[MAXN], ans[MAXN];
bool v[MAXN], s[MAXN];

void DFS(int idx)
{
   v[idx]=true;
   seg.push_back(idx);

   for(pair<int, int> node:adj[idx])
   {
      if(!v[node.first])
      {
         val[node.first]=node.second-val[idx];
         s[node.first]=!s[idx];

         DFS(node.first);
      }
   }

   return;
}

double GetValue(double x1, bool s1, double x2, bool s2)
{
   if(s1==s2)
   {
      if(x1-x2==0)
      {
         return INF;
      }

      return -INF;
   }

   if(s1)
   {
      return -(x1-x2)/2;
   }

   return (x1-x2)/2;
}

double GetSum(double x)
{
   double res=0;
   for(int node:seg)
   {
      if(s[node])
      {
         res+=abs(val[node]+x);
      }
      else
      {
         res+=abs(val[node]-x);
      }
   }

   return res;
}

bool AssignValues(int idx)
{
   seg.clear();

   val[idx]=0;
   s[idx]=true;

   DFS(idx);

   double x=INF;
   for(int node:seg)
   {
      for(pair<int, int> u:adj[node])
      {
         double temp=GetValue(val[u.first], s[u.first], u.second-val[node], !s[node]);

         if(temp==-INF)
         {
            return false;
         }

         if(temp==INF)
         {
            continue;
         }

         if(x==INF)
         {
            x=temp;
         }
         else if(x!=temp)
         {
            return false;
         }
      }
   }

   if(x==INF)
   {
      double res=INF;
      for(double i=-100; i<100; i+=0.5)
      {
         if(GetSum(i)<res)
         {
            x=i;
            res=GetSum(i);
         }
      }
   }

   for(int node:seg)
   {
      if(s[node])
      {
         ans[node]=val[node]+x;
      }
      else
      {
         ans[node]=val[node]-x;
      }
   }

   return true;
}

int main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);

   int n, m;
   cin >> n >> m;

   for(int i=0; i<m; i++)
   {
      int a, b, x;
      cin >> a >> b >> x;
      a--, b--;

      adj[a].push_back({b, x});
      adj[b].push_back({a, x});
   }

   for(int i=0; i<n; i++)
   {
      val[i]=0;
      v[i]=false;
   }

   for(int i=0; i<n; i++)
   {
      if(!v[i] && !AssignValues(i))
      {
         cout << "NO\n";

         return 0;
      }
   }

   cout << "YES\n";
   for(int i=0; i<n; i++)
   {
      cout << ans[i] << " ";
   }
   cout << "\n";

   return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 17 / 17
• Subtask 4: 24 / 24
• Subtask 5: 42 / 42