Submission #99218

#	Time	Username	Problem	Language	Result	Execution time	Memory
99218		eriksuenderhauf	Ancient Books (IOI17_books)	C++11	100 / 100	330 ms	26744 KiB

books

#include <bits/stdc++.h>
#include "books.h"
using namespace std;
typedef long long ll;
const int MAXN = 1e6 + 50;
int L[MAXN], R[MAXN], vis1[MAXN], vis2[MAXN];
int ind[MAXN];

void ext(int& l, int& r) {
 int mL = min(l, min(L[ind[l]], L[ind[r]]));
 int mR = max(r, max(R[ind[l]], R[ind[r]]));
 while (mL < l || r < mR) {
  if (mL < l) {
   l--;
   mL = min(mL, L[ind[l]]);
   mR = max(mR, R[ind[l]]);
  } else {
   r++;
   mL = min(mL, L[ind[r]]);
   mR = max(mR, R[ind[r]]);
  }
 }
}

ll  minimum_walk(vector<int> p, int s) {
 int n = p.size();
 if (s != 0) {
  ll ret = 0;
  int l = s, r = s, c = 0;
  for (int i = 0; i < n; i++) ind[i] = -1;
  for (int i = 0; i < n; i++) {
   ret += (ll) abs(p[i] - i);
   if (ind[i] != -1) continue;
   int j = i;
   L[c] = i, R[c] = i;
   do {
    ind[j] = c;
//    L[c] = min(L[c], j);
    R[c] = max(R[c], j);
    j = p[j];
   } while(i != j);
   if (i != p[i])
    l = min(l, L[c]), r = max(r, R[c]);
   c++;
  }
  int curL = s, curR = s;
  do {
   ext(curL, curR);
   int c1 = 0, c2 = 0;
   int mL1 = curL, mR1 = curR;
   int f1 = 0, f2 = 0;
   while (l < mL1) {
    mL1--;
    c1 += 2;
    ext(mL1, mR1);
    if (mR1 > curR) {
     f1 = true;
     break;
    }
   }
   int mL2 = curL, mR2 = curR;
   while (mR2 < r) {
    mR2++;
    c2 += 2;
    ext(mL2, mR2);
    if (mL2 < curL) {
     f2 = true;
     break;
    }
   }
   if (f1 && f2)
    ret += min(c1, c2);
   else
    ret += c1 + c2;
   curL = min(mL1, mL2);
   curR = max(mR1, mR2);
  } while (l < curL || curR < r);
  return ret;
 }
 ll ret = 0;
 ll sum = 0;
 vis1[0] = 1;
 vis2[n] = 0;
 for (int i = 1; i < n; i++)
  vis1[i] = vis1[i-1] | (p[i] != i);
 for (int i = n - 1; i > 0; i--)
  vis2[i] = vis2[i + 1] | (p[i] != i);
 for (int i = 0; i < n; i++) {
  ret += (ll) abs(p[i] - i);
  sum += (ll) p[i];
  if (sum * 2 == 1ll * (ll) i * (1ll * (ll) i + 1) && i != n - 1 && vis1[i] && vis2[i + 1])
   ret += 2;
 }
 return ret;
}

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