Submission #270857

#	Time	Username	Problem	Language	Result	Execution time	Memory
270857		hamerin	Ancient Books (IOI17_books)	C++17	50 / 100	1315 ms	160948 KiB

books

#include "books.h"

#include <bits/stdc++.h>

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

using namespace std;

using i64 = long long;
using d64 = long double;
using pi = pair<int, int>;
using pli = pair<i64, i64>;
using ti = tuple<int, int, int>;
using tli = tuple<i64, i64, i64>;

#define iterall(cont) cont.begin(), cont.end()
#define prec(n) setprecision(n) << fixed

i64 minimum_walk(vector<int> p, int s) {
    const int N = p.size();

    vector<vector<int>> cycles;
    vector<set<int>> cyc_st;
    vector<int> cyc(N);

    vector<bool> vst(N);
    for (int i = 0; i < N; i++) {
        if (vst[i]) continue;

        cycles.emplace_back(vector<int>());
        cyc_st.emplace_back(set<int>());

        int cur = i;
        while (cycles.back().empty() || cur != i) {
            cycles.back().emplace_back(cur);
            cyc_st.back().emplace(cur);
            cyc[cur] = cycles.size() - 1;
            vst[cur] = true;
			cur = p[cur];
        }
    }

    i64 ans = 0;
    for (int i = 0; i < N; i++) ans += abs(i - p[i]);

    vector<pi> intervals;
    for (auto &st : cyc_st)
        if (st.size() > 1 || *st.begin() == s)
            intervals.emplace_back(*st.begin(), *prev(st.end()));

    sort(iterall(intervals));

    int M = 0;
    for (auto [l, r] : intervals) {
		if (l > M) ans += 2 * (l - M);
        M = max(r, M);
    }

    return ans;
}

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