Submission #46922

#	Time	Username	Problem	Language	Result	Execution time	Memory
46922		SpaimaCarpatilor	Ancient Books (IOI17_books)	C++17	100 / 100	1037 ms	249660 KiB

books

#include "books.h"
#include<bits/stdc++.h>

using namespace std;

int nr, N, BG, p[1000009], d[1000009], mars[1000009];
set < int > S;
vector < int > v[1000009];

void add (int node, int newD)
{
    if (d[node] != -1) return ;
    d[node] = newD, v[newD].push_back (node), S.erase (node);
    int l = node, r = p[node];
    if (l > r) swap (l, r);
    while (1)
    {
        auto it = S.lower_bound (l);
        if (it == S.end () || *it > r) break;
        add (*it, newD);
    }
}

long long minimum_walk (vector < int > pp, int ss)
{
    N = pp.size (), BG = ss + 1;
    for (int i=1; i<=N; i++)
        p[i] = pp[i - 1] + 1;
    long long ans = 0;
    int x = 0, y = 0;
    for (int i=1; i<=N; i++)
    {
        int curr = i - p[i];
        if (curr < 0) curr = -curr;
        ans += curr;
        int l = i, r = p[i];
        if (l > r) swap (l, r);
        mars[l] ++, mars[r] --;
        if (i != p[i] || i == BG)
        {
            if (x == 0) x = i;
            y = i;
        }
    }
    for (int i=1; i<N; i++)
        mars[i] += mars[i - 1];
    if (mars[BG - 1] != 0 || mars[BG] != 0)
    {
        int lft = BG, rgt = BG;
        while (mars[rgt] > 0) rgt ++;
        while (mars[lft - 1] > 0) lft --;
        for (int i=lft; i<=rgt; i++)
            S.insert (i), d[i] = -1;
        add (BG, 0);
        for (int i=0; !v[i].empty (); i++)
            for (auto it : v[i])
            {
                if (it > 1) add (it - 1, i + 1);
                if (it < N) add (it + 1, i + 1);
            }
        int maxi = 0;
        for (int i=lft; i<=rgt; i++)
            maxi = max (maxi, d[i]);
        ans += 2LL * maxi;
    }
    for (int i=x; i<y; i++)
        if (mars[i] == 0)
            ans += 2;
    return ans;
}

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