Submission #796346

#	Time	Username	Problem	Language	Result	Execution time	Memory
796346		t6twotwo	Fountain Parks (IOI21_parks)	C++17	30 / 100	106 ms	29416 KiB

parks

#include "parks.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct dsu {
    int n;
    vector<int> p, s;
    dsu(int n) : n(n), p(n), s(n, 1) {
        iota(p.begin(), p.end(), 0);
    }
    int find(int x) {
        return x == p[x] ? x : p[x] = find(p[x]);
    }
    int size(int x) {
        return s[find(x)];
    }
    bool same(int x, int y) {
        return find(x) == find(y);
    }
    bool unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return 0;
        }
        if (s[x] > s[y]) {
            swap(x, y);
        }
        p[x] = y;
        s[y] += s[x];
        return 1;
    }
};
constexpr int A = 200000;
int construct_roads(vector<int> X, vector<int> Y) {
    int N = X.size();
    vector f(7, vector(A + 3, -1));
    for (int i = 0; i < N; i++) {
        f[X[i]][Y[i]] = i;
    }
    dsu uf(N);
    vector<int> u, v, a, b, m(A + 1, -1), l(A + 1, -1), r(A + 1, -1);
    for (int y = 2; y <= A; y += 2) {
        for (int x = 2; x <= 6; x += 2) {
            if (f[x][y] != -1 && f[x][y + 2] != -1) {
                if (x == 4) {
                    m[y + 1] = u.size();
                }
                u.push_back(f[x][y]);
                v.push_back(f[x][y + 2]);
                a.push_back(x == 2 ? 1 : 7);
                b.push_back(y + 1);
                uf.unite(f[x][y], f[x][y + 2]);
            }
            if (x != 6 && f[x][y] != -1 && f[x + 2][y] != -1) {
                if (x == 2 && l[y - 2] == -1) {
                    l[y] = u.size();
                    u.push_back(f[x][y]);
                    v.push_back(f[x + 2][y]);
                    a.push_back(3);
                    b.push_back(-1);
                    uf.unite(f[x][y], f[x + 2][y]);
                }
                if (x == 4 && r[y - 2] == -1) {
                    r[y] = u.size();
                    u.push_back(f[x][y]);
                    v.push_back(f[x + 2][y]);
                    a.push_back(5);
                    b.push_back(-1);
                    uf.unite(f[x][y], f[x + 2][y]);
                }
            }
        }
    }
    if (uf.size(0) != N) {
        return 0;
    }
    vector<int> q(A, -1), s(A, -1), t(A, -1);
    for (int i = 1; i <= A; i++) {
        if (i % 2 == 1 && m[i] != -1) {
            if (s[i - 1] != 1) {
                a[m[i]] = 3;
                q[i] = 0;
            } else {
                assert(t[i - 1] != 1);
                a[m[i]] = 5;
                q[i] = 1;
            }
        }
        if (i % 2 == 0) {
            if (l[i] != -1) {
                if (q[i - 1] == 0) {
                    b[l[i]] = i + 1;
                    s[i] = 1;
                } else {
                    b[l[i]] = i - 1;
                    s[i] = 0;
                }
            }
            if (r[i] != -1) {
                if (q[i - 1] == 1) {
                    b[r[i]] = i + 1;
                    t[i] = 1;
                } else {
                    b[r[i]] = i - 1;
                    t[i] = 0;
                }
            }
        }
    }
    build(u, v, a, b);
    return 1;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 0 / 20
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30