Submission #974415

#	Time	Username	Problem	Language	Result	Execution time	Memory
974415		alextodoran	IOI Fever (JOI21_fever)	C++17	100 / 100	2340 ms	81316 KiB

fever

/**
 _  _   __  _ _ _  _  _ _
 |a  ||t  ||o    d | |o  |
| __    _| | _ | __|  _ |
| __ |/_  | __  /__\ / _\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N_MAX = 100000;

const int U = 0, R = 1, D = 2, L = 3;
const int RU = 4, RD = 5, LD = 6, LU = 7;

int N;
int X[N_MAX + 2], Y[N_MAX + 2];
int order[N_MAX + 2];

int dir[N_MAX + 2];

void get_dir () {
    dir[1] = R;
    for (int i = 2; i <= N; i++) {
        if (abs(X[i] - X[1]) > abs(Y[i] - Y[1])) {
            dir[i] = (X[i] < X[1] ? R : L);
        } else if (abs(Y[i] - Y[1]) > abs(X[i] - X[1])) {
            dir[i] = (Y[i] < Y[1] ? U : D);
        } else {
            if (X[i] < X[1]) {
                dir[i] = R;
            } else {
                dir[i] = (Y[i] < Y[1] ? U : D);
            }
        }
    }
}

unordered_map <int, vector <int>> V[8];

int find_higher (vector <int> &v, int val, int arr[]) {
    int l = 0, r = (int) v.size();
    while (l < r) {
        int mid = (l + r) / 2;
        if (val <= arr[v[mid]]) {
            r = mid;
        } else {
            l = mid + 1;
        }
    }
    return l;
}
int find_lower (vector <int> &v, int val, int arr[]) {
    int l = 0, r = (int) v.size();
    while (l < r) {
        int mid = (l + r) / 2;
        if (arr[v[mid]] <= val) {
            r = mid;
        } else {
            l = mid + 1;
        }
    }
    return l;
}

int min_last[N_MAX + 2][8];
bool seen[N_MAX + 2][8];

priority_queue <tuple <int, int, int>> q;

void consider (int i, int t, int last) {
    if (last < min_last[i][t]) {
        min_last[i][t] = last;
        q.push(make_tuple(-last, i, t));
    }
}

void process (int i, int ti) {
    for (int t = 0; t < 8; t++) {
        int key;
        bool positive;
        bool go;
        if (t < 4) {
            go = (dir[i] == t);
            key = (t % 2 == 0 ? X[i] : Y[i]);
            positive = (t < 2);
        } else {
            go = (dir[i] == t - 4 || dir[i] == (t - 4 + 1) % 4);
            key = (t % 2 == 0 ? X[i] - Y[i] : X[i] + Y[i]);
            positive = (t < 6);
        }
        int *arr = (t == 0 || t == 2 ? Y : X);
        int coef = (t < 4 ? 1 : 2);
        vector <int> &v = V[t][key];
        if (t == ti) {
            int a;
            if (positive == true) {
                a = find_higher(v, arr[i], arr) + 1;
            } else {
                a = find_lower(v, arr[i], arr) + 1;
            }
            if (a < (int) v.size()) {
                consider(v[a], t, min_last[i][ti] + abs(arr[v[a]] - arr[i]) * coef);
            }
        }
        if (go == false) {
            continue;
        }
        int dist = (coef == 2 ? (min_last[i][ti] + 1) / 2 : min_last[i][ti]);
        int b;
        if (positive == true) {
            b = find_higher(v, arr[i] + dist, arr);
        } else {
            b = find_lower(v, arr[i] - dist, arr);
        }
        if (b < (int) v.size()) {
            consider(v[b], t, abs(arr[v[b]] - arr[i]) * coef);
        }
    }
}

int solve () {
    get_dir();
    iota(order + 1, order + N + 1, 1);
    sort(order + 1, order + N + 1, [&] (const int &i, const int &j) {
        return make_pair(X[i], Y[i]) < make_pair(X[j], Y[j]);
    });
    for (int k = 1; k <= N; k++) {
        int i = order[k];
        V[U][X[i]].push_back(i);
        V[R][Y[i]].push_back(i);
        V[RU][X[i] - Y[i]].push_back(i);
        V[RD][X[i] + Y[i]].push_back(i);
    }
    for (int k = N; k >= 1; k--) {
        int i = order[k];
        V[D][X[i]].push_back(i);
        V[L][Y[i]].push_back(i);
        V[LD][X[i] - Y[i]].push_back(i);
        V[LU][X[i] + Y[i]].push_back(i);
    }
    for (int i = 1; i <= N; i++) {
        for (int t = 0; t < 8; t++) {
            min_last[i][t] = INT_MAX;
            seen[i][t] = false;
        }
    }
    process(1, -1);
    while (q.empty() == false) {
        int i = get <1> (q.top()), t = get <2> (q.top());
        q.pop();
        if (seen[i][t] == true) {
            continue;
        }
        seen[i][t] = true;
        process(i, t);
    }
    int cnt = 0;
    for (int i = 1; i <= N; i++) {
        for (int t = 0; t < 8; t++) {
            if (seen[i][t] == true) {
                cnt++;
                break;
            }
        }
    }
    for (int t = 0; t < 8; t++) {
        V[t].clear();
    }
    return cnt;
}

void rot90 () {
    for (int i = 1; i <= N; i++) {
        swap(X[i], Y[i]); X[i] = -X[i];
    }
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> N;
    for (int i = 1; i <= N; i++) {
        cin >> X[i] >> Y[i];
    }
    int answer = solve();
    rot90(); answer = max(answer, solve());
    rot90(); answer = max(answer, solve());
    rot90(); answer = max(answer, solve());
    cout << answer << "\n";

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 6 / 6
• Subtask 4: 6 / 6
• Subtask 5: 12 / 12
• Subtask 6: 32 / 32
• Subtask 7: 31 / 31