Submission #1048708

#	Time	Username	Problem	Language	Result	Execution time	Memory
1048708		becaido	Ancient Books (IOI17_books)	C++17	22 / 100	2070 ms	38368 KiB

books

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include <bits/stdc++.h>
using namespace std;

#ifdef WAIMAI
#include "grader.cpp"
#else
#include "books.h"
#endif

#ifdef WAIMAI
#define debug(HEHE...) cout << "[" << #HEHE << "] : ", dout(HEHE)
void dout() {cout << '\n';}
template<typename T, typename...U>
void dout(T t, U...u) {cout << t << (sizeof...(u) ? ", " : ""), dout(u...);}
#else
#define debug(...) 7122
#endif

#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for (int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second

const int INF = 1e9;
const int SIZE = 1e6 + 5;

int n, L, R;
int p[SIZE];
bool vs[SIZE];
int l[SIZE], r[SIZE];
int d[SIZE], in[SIZE], out[SIZE], dis[SIZE];

ll minimum_walk(vector<int> p_, int s) {
    n = p_.size();
    s++;
    FOR (i, 1, n) {
        p[i] = p_[i - 1] + 1;
        in[i] = out[i] = vs[i] = 0;
    }

    FOR (i, 1, n) {
        if (i < p[i]) {
            out[i]++, out[p[i]]--;
            in[i + 1]++, in[p[i] + 1]--;
            d[i]++, d[p[i]]--;
        } else {
            out[p[i] + 1]++, out[i + 1]--;
            in[p[i]]++, in[i]--;
            d[p[i]]++, d[i]--;
        }
    }
    FOR (i, 1, n) {
        in[i] += in[i - 1];
        out[i] += out[i - 1];
        d[i] += d[i - 1];
    }

    L = 1, R = n;
    while (R > s && d[R - 1] == 0) R--;
    while (L < s && d[L] == 0) L++;
    if (L == R) return 0;

    FOR (i, L, R) if (vs[i] == 0) {
        int mn = n, mx = 1, x = i;
        vector<int> v;
        while (vs[x] == 0) {
            mn = min(mn, x);
            mx = max(mx, x);
            v.pb(x), vs[x] = 1, x = p[x];
        }
        for (int x : v) l[x] = mn, r[x] = mx;
    }

    FOR (i, L, R) {
        int cl = l[i], cr = r[i];
        FOR (j, l[i], r[i]) {
            cl = min(cl, l[j]);
            cr = max(cr, r[j]);
        }
        while (cl < l[i] || cr > r[i]) {
            int ml = cl, mr = cr;
            FOR (j, cl, l[i] - 1) {
                ml = min(ml, l[j]);
                mr = max(mr, r[j]);
            }
            FOR (j, r[i] + 1, cr) {
                ml = min(ml, l[j]);
                mr = max(mr, r[j]);
            }
            l[i] = cl, r[i] = cr;
            cl = ml, cr = mr;
        }
    }

    ll ans = 0;
    FOR (i, L, R) ans += out[i];

    FOR (i, L, R) dis[i] = INF, vs[i] = 0;
    deque<int> q;
    dis[s] = 0, q.pb(s);
    while (q.size()) {
        int pos = q.front();
        q.pop_front();
        if (vs[pos]) continue;
        auto upd = [&](int l, int r, int d, int t) {
            FOR (i, l, r) if (d < dis[i]) {
                dis[i] = d;
                if (t == 0) q.emplace_front(i);
                else q.pb(i);
            }
        };
        upd(l[pos], r[pos], dis[pos], 0);
        if (pos - 1 > L) upd(pos - 1, pos - 1, dis[pos] + 1, 1);
        if (pos + 1 < R) upd(pos + 1, pos + 1, dis[pos] + 1, 1);
    }
    ans += 2 * *max_element(dis + L, dis + R + 1);

    return ans;
}

/*
in1
4 0
0 2 3 1
out1
6
*/

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