제출 #1348273

#제출 시각아이디문제언어결과실행 시간메모리
1348273huutuanSplit the Attractions (IOI19_split)C++20
18 / 100
35 ms16428 KiB
#include "split.h"

#include <bits/stdc++.h>

using namespace std;

const int N=1e5+10;
int n, a, b, c, m;
vector<int> g[N];

namespace sub1{
   bool check(){
      for (int i=0; i<n; ++i) if ((int)g[i].size()>2) return 0;
      return 1;
   }
   vector<int> path;
   int vis[N];
   void dfs(int u){
      vis[u]=1;
      path.push_back(u);
      for (int v:g[u]) if (!vis[v]) dfs(v);
   }
   vector<int> solve(){
      int u=0;
      for (int i=0; i<n; ++i) if (g[i].size()==1) u=i;
      dfs(u);
      vector<int> ans(n);
      for (int i=0; i<n; ++i){
         if (i<a) ans[path[i]]=1;
         else if (i<a+b) ans[path[i]]=2;
         else ans[path[i]]=3;
      }
      return ans;
   }
}

namespace sub2{
   int num[N], low[N], joint[N], tdfs;
   bool check(){
      return a==1;
   }
   void dfs(int u, int p){
      num[u]=low[u]=++tdfs;
      int cc=0;
      for (int v:g[u]) if (v!=p){
         if (!num[v]){
            ++cc;
            dfs(v, u);
            low[u]=min(low[u], low[v]);
            if (low[v]>=num[u]) joint[u]=1;
         }else low[u]=min(low[u], num[v]);
      }
      if (p==-1) joint[u]=cc>=2;
   }
   void dfs2(int u, int &cnt, vector<int> &ans){
      if (cnt==0) return;
      ans[u]=2;
      --cnt;
      if (cnt==0) return;
      for (int v:g[u]) if (ans[v]==3){
         dfs2(v, cnt, ans);
         if (cnt==0) return;
      }
   }
   vector<int> solve(){
      dfs(0, -1);
      int u=0;
      while (joint[u]) ++u;
      vector<int> ans(n, 3);
      ans[u]=1;
      dfs2(u==0?1:0, b, ans);
      return ans;
   }
}

namespace sub3{
   bool check(){
      return m==n-1;
   }
   int sz[N];
   void dfs(int u, int p){
      sz[u]=1;
      for (int v:g[u]) if (v!=p){
         dfs(v, u);
         sz[u]+=sz[v];
      }
   }
   vector<pair<int, int>> vv;
   void dfs2(int u, int &cnt, int z, vector<int> &ans){
      if (cnt==0) return;
      ans[u]=z;
      --cnt;
      if (cnt==0) return;
      for (int v:g[u]) if (ans[v]==vv[2].second){
         dfs2(v, cnt, z, ans);
         if (cnt==0) return;
      }
   }
   vector<int> solve(){
      vv={{a, 1}, {b, 2}, {c, 3}};
      sort(vv.begin(), vv.end());
      dfs(0, -1);
      vector<int> ans(n, vv[2].second);
      for (int i=0; i<n; ++i) for (int j:g[i]) if (sz[i]>sz[j]){
         if (sz[j]>=vv[0].first && n-sz[j]>=vv[1].first){
            ans[j]=vv[0].second;
            ans[i]=vv[1].second;
            dfs2(j, vv[0].first, vv[0].second, ans);
            dfs2(i, vv[1].first, vv[1].second, ans);
            return ans;
         }
      }
      return vector<int>(n);
   }
}

vector<int> find_split(int _n, int _a, int _b, int _c, vector<int> p, vector<int> q) {
   n=_n, a=_a, b=_b, c=_c;
   m=p.size();
   for (int i=0; i<n-1; ++i) g[p[i]].push_back(q[i]), g[q[i]].push_back(p[i]);
   if (sub1::check()) return sub1::solve();
   if (sub2::check()) return sub2::solve();
   if (sub3::check()) return sub3::solve();
   return vector<int>(n);
}
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