Submission #1030376

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030376		shiomusubi496	Ancient Books (IOI17_books)	C++17	12 / 100	5 ms	8280 KiB

books

#include "books.h"

#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); --i)

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)

using namespace std;

using ll = long long;

constexpr ll inf = 1e18;

template<class T, class U> bool chmin(T& a, const U& b) { return a > b ? a = b, true : false; }
template<class T, class U> bool chmax(T& a, const U& b) { return a < b ? a = b, true : false; }

long long minimum_walk(std::vector<int> p, int s) {
    int n = p.size();
    if (is_sorted(all(p))) return 0;
    ll ans = 0;
    {
        while (p.back() == n - 1) {
            if (s == n - 1) {
                --s;
                ans += 2;
            }
            p.pop_back();
            --n;
        }
        reverse(all(p));
        rep (i, n) p[i] = n - 1 - p[i];
        s = n - 1 - s;
        while (p.back() == n - 1) {
            if (s == n - 1) {
                --s;
                ans += 2;
            }
            p.pop_back();
            --n;
        }
        reverse(all(p));
        rep (i, n) p[i] = n - 1 - p[i];
        s = n - 1 - s;
    }
    rep (i, n) ans += abs(p[i] - i);
    vector<int> mns(n), mxs(n);
    {
        vector<bool> seen(n);
        rep (i, n) {
            if (seen[i]) continue;
            int j = i;
            int mx = 0;
            do {
                seen[j] = true;
                chmax(mx, j);
                j = p[j];
            } while (i != j);
            j = i;
            do {
                mns[j] = i;
                mxs[j] = mx;
                j = p[j];
            } while (i != j);
        }
    }

    vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, inf));
    dp[mns[s]][mxs[s]] = 0;
    rep (len, n) {
        rep (l, n + 1 - len) {
            int r = l + len;
            if (dp[l][r] == inf) continue;
            if (l != 0) chmin(dp[mns[l - 1]][max(r, mxs[l - 1])], dp[l][r] + 1);
            if (r != n - 1) chmin(dp[min(l, mns[r + 1])][mxs[r + 1]], dp[l][r] + 1);
        }
    }
    return ans + dp[0][n - 1] * 2;
}

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