Submission #759347

#	Time	Username	Problem	Language	Result	Execution time	Memory
759347		Sharky	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	220 ms	23712 KiB

supertrees

#include "supertrees.h"
#include <bits/stdc++.h>
using namespace std;

const int maxn = 1005;
int N, fa[maxn], sz[maxn];
bool ok = true;

int find(int u) {
    return (fa[u] == u) ? u : fa[u] = find(fa[u]);
}

bool merge(int u, int v) {
    u = find(u), v = find(v);
    if (u == v) return false;
    if (sz[v] > sz[u]) swap(u, v);
    fa[v] = u;
    sz[u] += sz[v];
    return true;
}

bool vis[maxn];
vector<int> edits;

void dfs(int u, vector<vector<int>>& ans, vector<vector<int>>& p) {
    vis[u] = true;
    edits.push_back(u);
    for (int i = 0; i < N; i++) {
        if (!vis[i] && p[u][i] == 1 && find(u) == find(i)) {
            ans[u][i] = ans[i][u] = 1;
            dfs(i, ans, p);
        }
    }
}

void process(vector<int> v, vector<vector<int>>& ans, vector<vector<int>>& p) {
    if ((int) v.size() == 1) return;
    // for (int i = 0; i < v.size(); i++) cout << v[i] << endl;
    int n = v.size(), cnt = 0;
    vector<int> cyc;
    vector<vector<int>> seen(N);
    vector<bool> in_cyc(N, 0);
    bool two = false;
    for (int i : v) {
        vector<bool> b(3, 0);
        for (int j = 0; j < N; j++) {
            if (i == j) continue;
            b[p[i][j]] = true;
            // cout << i << ' ' << j << ' ' << p[i][j] << '\n';
        }
        for (int j = 0; j < N; j++) {
            if (p[i][j] == 1) merge(i, j);
        }
        if (b[2] && !b[1]) {
            cyc.push_back(i);
            // cout << "in cycle!" << ' ' << i << endl;
            in_cyc[i] = true;
        }
        two = (two | b[2]);
    }
    // cout << "alive\n";
    for (int i = 0; i < n; i++) if (!in_cyc[v[i]]) {
        seen[find(v[i])].push_back(v[i]);
        // cout << "corresponding find: " << v[i] << ' ' << find(v[i]) << '\n';
    }
    // cout << "alive\n";
    for (int i = 0; i < N; i++) {
        if (seen[i].empty()) continue;
        dfs(seen[i].front(), ans, p);
        cyc.push_back(seen[i].front());
        in_cyc[seen[i].front()] = true;
        seen[find(seen[i].front())].push_back(seen[i].front());
        for (int j : edits) vis[j] = 0;
    }
    if (two && ((int) cyc.size() == 1 || (int) cyc.size() == 2)) {
        ok = false;
        return;
    }
    for (int i = 0; i < N; i++) if (!seen[i].empty()) cnt++;
    if (cnt > (int) cyc.size()) {
        ok = false;
        return;
    }
    for (int i = 0; i < cyc.size(); i++) {
        int nxt = (i + 1) % cyc.size();
        ans[cyc[i]][cyc[nxt]] = ans[cyc[nxt]][cyc[i]] = 1;
    }
}

int construct(std::vector<std::vector<int>> p) {
    int n = p[0].size();
    N = n;
    vector<vector<int>> ans(n, vector<int> (n, 0));
    for (int i = 0; i < n; i++) {
        fa[i] = i, sz[i] = 1;
        for (int j = 0; j < n; j++) {
            if (p[i][j] >= 3) return 0;
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (p[i][j]) merge(i, j);
        }
    }
    for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) {
        if (!p[i][j] && find(i) == find(j)) return 0;
    }
    vector<vector<int>> g(n);
    for (int i = 0; i < n; i++) g[find(i)].push_back(i);
    for (int i = 0; i < n; i++) fa[i] = i, sz[i] = 1;
    for (int i = 0; i < n; i++) {
        if (!g[i].empty()) {
            process(g[i], ans, p);
            if (!ok) return 0;
        }
    }
    for (int i = 0; i < n; i++) ans[i][i] = 0;
    build(ans);
    return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'void process(std::vector<int>, std::vector<std::vector<int> >&, std::vector<std::vector<int> >&)':
supertrees.cpp:84:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |     for (int i = 0; i < cyc.size(); i++) {
      |                     ~~^~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 10 / 10
• Subtask 3: 19 / 19
• Subtask 4: 35 / 35
• Subtask 5: 21 / 21
• Subtask 6: 4 / 4