Submission #46914

#	Time	Username	Problem	Language	Result	Execution time	Memory
46914		SpaimaCarpatilor	Ancient Books (IOI17_books)	C++17	50 / 100	253 ms	17300 KiB

books

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

using namespace std;

int nr, N, S, p[1000009], mars[1000009];
bool useful[1000009];

long long minimum_walk (vector < int > pp, int ss)
{
    N = pp.size (), S = ss + 1;
    for (int i=1; i<=N; i++)
        p[i] = pp[i - 1] + 1;
    long long ans = 0;
    for (int i=1; i<=N; i++)
    {
        int curr = i - p[i];
        if (curr < 0) curr = -curr;
        ans += curr;
    }
    for (int i=1; i<=N; i++)
        if (i != p[i])
        {
            int l = i, r = p[i];
            if (l > r) swap (l, r);
            mars[l] ++, mars[r] --;
            useful[i] = 1;
        }
    useful[S] = 1;
    int usefulToRight = 0, usefulToLeft = 0;
    for (int i=1; i<=N; i++)
        usefulToRight += useful[i];
    for (int i=1; i<N; i++)
        mars[i] += mars[i - 1];
    for (int i=1; i<N; i++)
    {
        usefulToRight -= useful[i];
        usefulToLeft += useful[i];
        if (usefulToLeft > 0 && usefulToRight > 0 && mars[i] == 0)
            ans += 2;
    }
    return ans;
}

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