Submission #395679

#	Time	Username	Problem	Language	Result	Execution time	Memory
395679		blue	Ancient Books (IOI17_books)	C++17	0 / 100	1 ms	204 KiB

books

#include "books.h"
#include <vector>
#include <cmath>
using namespace std;

/*
Permutations form cycles, we can efficiently go through an entire cycle.

If we want to go from u in cycle(u) to v in cycle(v), and we want to sort cycle C in the middle, we can
do so in length(C) + min{c in C, |u-c| + |c-v|}

Let R be a cycle such that min(R) is as large as possible.
*/


long long minimum_walk(vector<int> p, int s)
{
    long long res = 0;
    int n = p.size();
    vector<int> occ(n, 0);

    int D = 0;
    for(int i = 0; i < n; i++)
    {
        res += abs(p[i] - i);
        if(occ[i]) continue;
        if(p[i] != i)
            D = i;
        occ[i] = 1;
        for(int j = p[i]; j != i; j = p[j])
        {
            occ[j] = 1;
        }
    }
    res += 2*D;
    return res;
}

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