Submission #301560

#	Time	Username	Problem	Language	Result	Execution time	Memory
301560		kevinsogo	Comparing Plants (IOI20_plants)	C++17	30 / 100	4069 ms	100676 KiB

plants

#include "plants.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int mod(int a, int n) {
    if ((a %= n) < 0) a += n;
    return a;
}

int n, k;
int dist(int i, int j) {
    return mod(j - i - 1, n) + 1;
}



struct Tree {
    int k;
    vector<vector<int>> anc;
    vector<vector<ll>> ancd;
    Tree() {}
    Tree(const vector<int>& par, const vector<ll>& pard) {
        int n = par.size();
        for (k = 0; 1 << k <= n; k++);
        anc = vector<vector<int>>(k, vector<int>(n, -1));
        ancd = vector<vector<ll>>(k, vector<ll>(n, -1));
        anc[0] = par;
        ancd[0] = pard;
        for (int kk = 0; kk < k - 1; kk++) {
            for (int i = 0; i < n; i++) {
                int j = anc[kk][i];
                anc[kk + 1][i] = anc[kk][j];
                ancd[kk + 1][i] = ancd[kk][i] + ancd[kk][j];
            }
        }
    }

    pair<int,ll> walk_up(int i, ll d) {
        for (int kk = k; kk--;) {
            if (d >= ancd[kk][i]) {
                d -= ancd[kk][i];
                i = anc[kk][i];
            }
        }
        return {i, d};
    }
};

vector<int> vals;
Tree rttree, lftree;
void init(int k_, vector<int> r) {
    k = k_;
    n = r.size();
    vals = vector<int>(n);

    vector<int> likod(n), harap(n);
    unordered_set<int> oks;

    vector<int> cands;
    for (int i = 0; i < n; i++) if (r[i] == 0) cands.push_back(i);
    for (int x2 = 0, x1 = cands.size() - 1; x2 < cands.size(); x1 = x2++) {
        int j1 = cands[x1], j2 = cands[x2];
        harap[j1] = j2;
        likod[j2] = j1;
        if (dist(j1, j2) >= k) oks.insert(j2);
    }
    
    for (int v = n; v; v--) {
        int j = *oks.begin();
        int j1 = likod[j], j2 = harap[j];
        oks.erase(j);
        vals[j] = v;
        r[j] += n + 1;
        vector<int> bagos;
        for (int l = j - k + 1; l < j; l++) {
            int ln = mod(l, n);
            if (!--r[ln]) bagos.push_back(ln);
        }

        if (v > 1) {
            if (j == j1 && j == j2) {
                j1 = bagos.back();
                j2 = bagos.front();
            }

            bagos.insert(bagos.begin(), j1);
            bagos.push_back(j2);
            for (int x1 = 0, x2 = 1; x2 < bagos.size(); x1++, x2++) {
                int j1 = bagos[x1], j2 = bagos[x2];
                harap[j1] = j2;
                likod[j2] = j1;
                if (dist(j1, j2) >= k) {
                    oks.insert(j2);
                } else if (oks.count(j2)) {
                    oks.erase(j2);
                }
            }
        }
    }

    vector<int> lfs(n, -1), rts(n, -1);
    vector<int> wals(n, -1), inds(n);
    iota(inds.begin(), inds.end(), 0);
    sort(inds.begin(), inds.end(), [&](int i, int j) { return vals[i] < vals[j]; });
    for (int x : inds) {
        wals[x] = 0;
        lfs[x] = rts[x] = x;
        for (int i = x - k + 1; i <= x; i++) {
            if (wals[lfs[x]] < wals[mod(i, n)]) lfs[x] = mod(i, n);
        }
        for (int i = x; i < x + k; i++) {
            if (wals[rts[x]] < wals[mod(i, n)]) rts[x] = mod(i, n);
        }
        wals[x] = vals[x];
    }

    vector<ll> lfdists(n);
    vector<ll> rtdists(n);
    for (int i = 0; i < n; i++) {
        lfdists[i] = dist(lfs[i], i);
        rtdists[i] = dist(i, rts[i]);
    }

    lftree = Tree(lfs, lfdists);
    rttree = Tree(rts, rtdists);
}

bool is_fixed_right(int x, int y) {
    auto [X, rem] = rttree.walk_up(x, dist(x, y));
    return rem < k && vals[X] >= vals[y];
}

bool is_fixed_left(int x, int y) {
    auto [X, rem] = lftree.walk_up(x, dist(y, x));
    return rem < k && vals[X] >= vals[y];
}

int compare_plants(int x, int y) {
    int mul = 1;
    if (vals[x] < vals[y]) {
        swap(x, y);
        mul = -1;
    }

    return (is_fixed_right(x, y) || is_fixed_left(x, y)) * mul;
}

Compilation message (stderr)

plants.cpp: In function 'void init(int, std::vector<int>)':
plants.cpp:62:48: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for (int x2 = 0, x1 = cands.size() - 1; x2 < cands.size(); x1 = x2++) {
      |                                             ~~~^~~~~~~~~~~~~~
plants.cpp:89:41: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |             for (int x1 = 0, x2 = 1; x2 < bagos.size(); x1++, x2++) {
      |                                      ~~~^~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 14 / 14
• Subtask 3: 0 / 13
• Subtask 4: 0 / 17
• Subtask 5: 11 / 11
• Subtask 6: 0 / 15
• Subtask 7: 0 / 25