Submission #893195

#	Time	Username	Problem	Language	Result	Execution time	Memory
893195		vjudge1	Ancient Books (IOI17_books)	C++17	0 / 100	1 ms	348 KiB

books

#include "books.h"

#include <bits/stdc++.h>

using namespace std;

using vi = vector<int>;
using ii = pair<int, int>;

struct UF {
    vi e;
    UF(int N) : e(N, -1) {}
    int repr(int u) {
        while(e[u] >= 0) u = e[u];
        return u;
    }

    int join(int u, int v) {
        u = repr(u);
        v = repr(v);
        if(u == v) return 0;
        if(e[u] >= e[v]) swap(u, v);
        e[u] += e[v];
        e[v] = u;
        return 1;
    }
};

long long minimum_walk(vi p, int s) {
    int n = p.size();
    vi ip(n);
    for(int i = 0; i < n; ++i)
        ip[p[i]] = i;
    int re = 0, nrcic = 0;
    vi vis(n, 0), cul(n, 0), alb(n, 0);
    for(int i = 0; i < n; ++i) {
        if(!vis[i]) {
            int u = i;
            while(!vis[u]) {
                vis[u] = 1;
                cul[u] = nrcic;
                u = p[u];
            }
            alb[nrcic] = (i == p[i]);
            nrcic++;
        }
    }
  //  cout << "alb: ";
  //  for(auto it : alb) cout << it << " ";
  //  cout << "\n";
    vector<vi> L(nrcic);
    for(int i = 0; i + 1 < n; ++i) {
        if(cul[i] != cul[i + 1]) {
            L[cul[i]].push_back(cul[i + 1]);
            L[cul[i + 1]].push_back(cul[i]);
        }
    }
    for(int i = 0; i < nrcic; ++i) {
        sort(L[i].begin(), L[i].end());
        L[i].resize(unique(L[i].begin(), L[i].end()) - L[i].begin());
    }
    for(int i = 0; i < n; ++i)
        re += abs(i - p[i]);
    int rec = alb[cul[s]];
    for(int i = 0; i < nrcic; ++i)
        rec += !alb[i];
    vi viz(nrcic, 0);

    function<void(int, vi&, int&nr)> dfs0 = [&](int u, vi& V, int &nr) {
        viz[u] = 1;
        ++nr;
        for(auto it : L[u]) {
            if(!viz[it]) {
                if(alb[it]) {
                    dfs0(it, V, nr);
                } else {
                    V.push_back(it);
                }
            }
        }
    };

    vector<pair<int, ii> > E;

    for(int i = 0; i < nrcic; ++i) {
        if(alb[i] && !viz[i]) {
            vi vecini;
            int w = 0;
            dfs0(i, vecini, w);
            if(vecini.size() == 2) {
                int u = vecini[0], v = vecini[1];
                E.push_back({w, ii{u, v}});
            }
        }
    }
    for(int i = 0; i < nrcic; ++i) {
        for(auto it : L[i])
            if(!alb[i] && !alb[it])
                E.push_back({0, ii{i, it}});
    }
    sort(E.begin(), E.end());

    UF Sol(nrcic);
    for(auto [w, muchie] : E) {
        auto [u, v] = muchie;

        if(Sol.join(u, v)) {
            rec += w; 
        }
    }

	return re + 2 * (rec - 1);
}

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