Submission #301568

#	Time	Username	Problem	Language	Result	Execution time	Memory
301568		kevinsogo	Comparing Plants (IOI20_plants)	C++17	100 / 100	1578 ms	137536 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 MinTree {
    int i, j;
    int m, a = 0;
    MinTree *l, *r;
    MinTree(const vector<int>& v, int i, int j): i(i), j(j) {
        if (j - i == 1) {
            m = v[i];
            l = r = nullptr;
        } else {
            int k = i + j >> 1;
            l = new MinTree(v, i, k);
            r = new MinTree(v, k, j);
            m = min(l->m, r->m);
        }
    }

    void visit() {
        if (a) {
            m += a;
            if (l) l->a += a, r->a += a;
            a = 0;
        }
    }
    
    void inc(int I, int J, int A) {
        if (I <= i && j <= J) {
            a += A;
            visit();
        } else {
            visit();
            if (!(J <= i || j <= I)) {
                l->inc(I, J, A);
                r->inc(I, J, A);
                m = min(l->m, r->m);
            }
        }
    }

    void get0s(int I, int J, vector<int>& t) {
        visit();
        if (m > 0 || J <= i || j <= I) return;
        if (l) {
            l->get0s(I, J, t);
            r->get0s(I, J, t);
        } else {
            t.push_back(i);
        }
    }
};

struct MaxTree {
    int i, j;
    pair<int,int> m;
    MaxTree *l, *r;
    MaxTree(int v, int i, int j): i(i), j(j), m(v, i) {
        if (j - i == 1) {
            l = r = nullptr;
        } else {
            int k = i + j >> 1;
            l = new MaxTree(v, i, k);
            r = new MaxTree(v, k, j);
        }
    }

    void write(int I, int v) {
        if (i <= I && I < j) {
            if (l) {
                l->write(I, v);
                r->write(I, v);
                m = std::max(l->m, r->m);
            } else {
                m = {v, i};
            }
        }
    }

    pair<int,int> max(int I, int J) {
        if (I <= i && j <= J) {
            return m;
        } else if (J <= i || j <= I) {
            return {-2, -2};
        } else {
            return std::max(l->max(I, J), r->max(I, J));
        }
    }
};

struct TreeTree {
    int k;
    vector<vector<int>> anc;
    vector<vector<ll>> ancd;
    TreeTree() {}
    TreeTree(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;
TreeTree rttree, lftree;
void init(int k_, vector<int> r) {
    k = k_;
    n = r.size();
    vals = vector<int>(n);

    MinTree curr(r, 0, n);
    vector<int> likod(n), harap(n);
    unordered_set<int> oks;

    vector<int> cands;
    for (int i = 0; i < n; i++) if (!r[i]) 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;
        curr.inc(j, j + 1, n + 1);
        curr.inc(j - k + 1 + n, j + n, -1);
        curr.inc(j - k + 1, j, -1);

        vector<int> bagos;
        curr.get0s(j - k + 1 + n, j + n, bagos);
        curr.get0s(j - k + 1, j, bagos);

        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);
    MaxTree wals(-1, 0, n);
    vector<int> 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.write(x, 0);
        int m;
        tie(m, lfs[x]) = max(wals.max(x - k + 1, x + 1), wals.max(x - k + 1 + n, x + 1 + n));
        tie(m, rts[x]) = max(wals.max(x, x + k), wals.max(x - n, x + k - n));
        wals.write(x, vals[x]);
    }

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

    lftree = TreeTree(lfs, lfdists);
    rttree = TreeTree(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 constructor 'MinTree::MinTree(const std::vector<int>&, int, int)':
plants.cpp:25:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   25 |             int k = i + j >> 1;
      |                     ~~^~~
plants.cpp: In constructor 'MaxTree::MaxTree(int, int, int)':
plants.cpp:74:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   74 |             int k = i + j >> 1;
      |                     ~~^~~
plants.cpp: In function 'void init(int, std::vector<int>)':
plants.cpp:148:48: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  148 |     for (int x2 = 0, x1 = cands.size() - 1; x2 < cands.size(); x1 = x2++) {
      |                                             ~~~^~~~~~~~~~~~~~
plants.cpp:176:41: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  176 |             for (int x1 = 0, x2 = 1; x2 < bagos.size(); x1++, x2++) {
      |                                      ~~~^~~~~~~~~~~~~~

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