#include "race.h" #include <bits/stdc++.h> using namespace std; #define pb push_back const int N=200050; int ans=N,sz[N],K,cnt[5*N],mn[5*N]; vector<pair<int,int>> E[N]; bool was[N]; int DFS(int u,int p){sz[u]=1;for(auto e:E[u])if(e.first!=p&&!was[e.first])DFS(e.first,u),sz[u]+=sz[e.first];} int Find(int u,int p,int n){for(auto e:E[u])if(e.first!=p&&!was[e.first]&&sz[e.first]*2>n)return Find(e.first,u,n);return u;} int FindCentroid(int u){DFS(u,u);return Find(u,u,sz[u]);} vector<pair<int,int>> all; void Solve(int u,int p,int dep,int len){ if(dep>K)return; //printf("%i %i %i %i\n",u,p,dep,len); all.pb({dep,len}); if(K>=dep&&cnt[K-dep]==1)ans=min(ans,len+mn[K-dep]); for(auto e:E[u])if(!was[e.first]&&e.first!=p)Solve(e.first,u,dep+e.second,len+1); } void Decompose(int u){ u=FindCentroid(u); was[u]=1; for(int i=0;i<5*N;i++)mn[i]=0,cnt[i]=0; cnt[0]=1; for(auto e:E[u]){ if(!was[e.first]){ Solve(e.first,u,e.second,1); for(auto c:all){ if(cnt[c.first]==0)cnt[c.first]=1,mn[c.first]=c.second; else mn[c.first]=min(mn[c.first],c.second); } all.clear(); } } for(auto e:E[u])if(!was[e.first])Decompose(e.first); } int best_path(int n,int k,int h[][2],int l[]){ K=k; for(int i=0;i<n-1;i++){ int u=h[i][0],v=h[i][1],w=l[i]; E[u].pb({v,w}); E[v].pb({u,w}); } Decompose(0); if(ans==N)return -1; else return ans; }

race.cpp: In function 'int DFS(int, int)':
race.cpp:9:109: warning: no return statement in function returning non-void [-Wreturn-type]
    9 | int DFS(int u,int p){sz[u]=1;for(auto e:E[u])if(e.first!=p&&!was[e.first])DFS(e.first,u),sz[u]+=sz[e.first];}
      |                                                                                                             ^