Submission #1037090

#	Time	Username	Problem	Language	Result	Execution time	Memory
1037090		huutuan	Ancient Books (IOI17_books)	C++14	50 / 100	137 ms	183308 KiB

books

#include "books.h"

#include <bits/stdc++.h>

using namespace std;

const int N=1e6, LG=20;
int tl, tr;
int vis[N], n, stmin[LG][N], stmax[LG][N];
pair<int, int> ll[N], rr[N];
int check[N];
long long ans=0;

int getmin(int l, int r){
   int lg=__lg(r-l+1);
   return min(stmin[lg][l], stmin[lg][r-(1<<lg)+1]);
}

int getmax(int l, int r){
   int lg=__lg(r-l+1);
   return max(stmax[lg][l], stmax[lg][r-(1<<lg)+1]);
}

void extend(int &l, int &r){
   while (1){
      int nl=getmin(l, r), nr=getmax(l, r);
      if (nl==l && nr==r) break;
      l=nl; r=nr;
   }
}

void dp(int l, int r){
   extend(l, r);
   if (l==tl && r==tr) return;
   int l1=tl, r1=r, l2=l, r2=tr;
   if (ll[l].first || ll[l].second){
      l1=ll[l].first;
   }
   if (rr[r].first || rr[r].second){
      r2=rr[r].second;
   }
   int c1=check[l]-check[l1];
   int c2=check[r2]-check[r];
   if (l1==l) c1=1e9;
   if (r2==r) c2=1e9;
   ans+=min(c1, c2)*2;
   if (c1<=c2) return dp(l1, r1);
   return dp(l2, r2);
}

long long minimum_walk(vector<int> p, int s) {
   n=p.size();
   for (int i=0; i<n; ++i) if (!vis[i]){
      vector<int> cc;
      int u=i;
      stmin[0][i]=i; stmax[0][i]=i;
      int maxl=-1, minr=-1;
      while (!vis[u]){
         if (u<s){
            if (maxl==-1 || maxl<u) maxl=u;
         }
         if (u>s){
            if (minr==-1 || minr>u) minr=u;
         }
         vis[u]=1;
         cc.push_back(u);
         stmin[0][i]=min(stmin[0][i], u);
         stmax[0][i]=max(stmax[0][i], u);
         ans+=abs(u-p[u]);
         u=p[u];
      }
      if (stmin[0][i]<s && s<stmax[0][i]){
         ll[stmin[0][i]+1]=rr[stmax[0][i]-1]={maxl, minr};
      }else{
         int l=stmin[0][i], r=stmax[0][i];
         ++check[l]; --check[r];
      }
      for (int j:cc) stmin[0][j]=stmin[0][i], stmax[0][j]=stmax[0][i];
   }
   partial_sum(check, check+n, check);
   for (int i=n-1; i>0; --i) check[i]=!check[i-1];
   check[0]=0;
   partial_sum(check, check+n, check);
   for (int i=1; i<=s; ++i){
      if (ll[i].first==0 && ll[i].second==0) ll[i]=ll[i-1];
   }
   for (int i=n-2; i>=s; --i){
      if (rr[i].first==0 && rr[i].second==0) rr[i]=rr[i+1];
   }
   for (int i=1; i<LG; ++i) for (int j=0; j+(1<<i)-1<n; ++j){
      stmin[i][j]=min(stmin[i-1][j], stmin[i-1][j+(1<<(i-1))]);
      stmax[i][j]=max(stmax[i-1][j], stmax[i-1][j+(1<<(i-1))]);
   }
   tl=0, tr=n-1;
   while (tl<s && stmin[0][tl]==tl && stmax[0][tl]==tl) ++tl;
   while (tr>s && stmin[0][tr]==tr && stmax[0][tr]==tr) --tr;
   dp(s, s);
   return ans;
}

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 28 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30