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  1. //NiceDuck
  2. #include "bits/stdc++.h"
  3. typedef long long ll;
  4. using namespace std;
  5. #define FILE "000"
  6. #define foru(i,a,b) for(int i=(int)(a); i<=(int)(b); ++i)
  7. #define ford(i,a,b) for(int i=(int)(a); i>=(int)(b); --i)
  8. #define fastio ios_base::sync_with_stdio(0);cin.tie(0);
  9. #define pb push_back
  10. #define fi first
  11. #define se second
  12. #define el "\n"
  13. #define MASK(i) (1LL<<(i))
  14. #define BIT(i,j) (((i)>>(j))&1)
  15. #define TIME 1.0*clock()/CLOCKS_PER_SEC
  16. #define LOG 20
  17.  
  18. const ll MAX=2e5+5;
  19. int n,q,cnt;
  20. struct Dsu
  21. {
  22.     vector<pair<int,int> > history;
  23.     int par[MAX],sz[MAX];
  24.     void init()
  25.     {
  26.         foru(i,1,n)
  27.         {
  28.             par[i]=i;
  29.             sz[i]=1;
  30.         }
  31.     }
  32.     int find_par(int x)
  33.     {
  34.         while(x!=par[x]) x=par[x];
  35.         return x;
  36.     }
  37.     int join(int u, int v)
  38.     {
  39.         u=find_par(u); v=find_par(v);
  40.         if(u==v)
  41.         {
  42.             history.pb({-1,-1});
  43.             return 0;
  44.         }
  45.         if(sz[u]<sz[v]) swap(u,v);
  46.         history.pb({v,sz[u]});
  47.         sz[u]+=sz[v];
  48.         par[v]=u;
  49.         return -1;
  50.     }
  51.     int rollback(int ver)
  52.     {
  53.         int res=0;
  54.         while((int)history.size()>ver)
  55.         {
  56.             pair<int,int> pa=history.back();
  57.             history.pop_back();
  58.             if(pa.fi==-1) continue;
  59.             int v=pa.fi, old=pa.se;
  60.             int u=par[v];
  61.             sz[u]=old;
  62.             par[v]=v;
  63.             ++res;
  64.         }
  65.         return res;
  66.     }
  67. } dsu;
  68.  
  69. int main()
  70. {
  71.     fastio
  72.     if(fopen(FILE ".inp","r"))
  73.     {
  74.         freopen(FILE ".inp","r",stdin); freopen(FILE ".out","w",stdout);
  75.     }
  76.     cin>>n>>q;
  77.     cnt=n;
  78.     dsu.init();
  79.     cin.ignore();
  80.     vector<int> v;
  81.     v.clear();
  82.     while(q--)
  83.     {
  84.         string str; cin>>str;
  85.         if(str=="persist") v.pb(dsu.history.size());
  86.         else if(str=="union")
  87.         {
  88.             int u,v; cin>>u>>v;
  89.             cnt+=dsu.join(u,v);
  90.             cout<<cnt<<el;
  91.         }
  92.         else
  93.         {
  94.             int x=v.back();
  95.             cnt+=dsu.rollback(x);
  96.             cout<<cnt<<el;
  97.             v.pop_back();
  98.         }
  99.     }
  100.     return 0;
  101. }
  102.  
Success #stdin #stdout 0.01s 5324KB
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https://ideone.com/SHGIT1
language:
C++14 (gcc 8.3)
created:
5 hours ago
visibility:
public

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