Submission #1196122

#	Time	Username	Problem	Language	Result	Execution time	Memory
1196122		islam_2010	Connecting Supertrees (IOI20_supertrees)	C++20	Compilation error	0 ms	0 KiB

supertrees

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

bool solve(vector<vector<int>>& p) {
    int n = p.size();
    
    for (int i = 0; i < n; ++i) {
        if (p[i][i] != 1) return false;
        for (int j = 0; j < n; ++j) {
            if (p[i][j] != p[j][i]) return false;
            if (p[i][j] > 2) return false;
        }
    }
    
    vector<vector<int>> b(n, vector<int>(n, 0));
    vector<int> parent(n);
    for (int i = 0; i < n; ++i) parent[i] = i;
    
    auto find = [&](int u) {
        while (parent[u] != u) {
            parent[u] = parent[parent[u]];
            u = parent[u];
        }
        return u;
    };
    
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            if (p[i][j] == 1) {
                int root_i = find(i);
                int root_j = find(j);
                if (root_i == root_j) {
                    return false;
                }
                parent[root_j] = root_i;
                b[i][j] = b[j][i] = 1;
            }
        }
    }
    
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            if (p[i][j] == 2) {
                if (find(i) != find(j)) {
                    return false;
                }
                bool found = false;
                for (int k = 0; k < n; ++k) {
                    if (k != i && k != j && b[i][k] == 1 && b[k][j] == 1) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    return false;
                }
            }
        }
    }
    
    return true;
}

int construct(vector<vector<int>> p) {
    if (!solve(p)) {
        return 0;
    }
    
    int n = p.size();
    vector<vector<int>> b(n, vector<int>(n, 0));
    vector<int> parent(n);
    for (int i = 0; i < n; ++i) parent[i] = i;
    
    auto find = [&](int u) {
        while (parent[u] != u) {
            parent[u] = parent[parent[u]];
            u = parent[u];
        }
        return u;
    };
    
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            if (p[i][j] == 1) {
                int root_i = find(i);
                int root_j = find(j);
                parent[root_j] = root_i;
                b[i][j] = b[j][i] = 1;
            }
        }
    }
    
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; j < n; ++j) {
            if (p[i][j] == 2 && b[i][j] == 0) {
                bool added = false;
                for (int k = 0; k < n; ++k) {
                    if (k != i && k != j && b[i][k] == 1 && b[k][j] == 1) {
                        added = true;
                        break;
                    }
                }
                if (!added) {
                    b[i][j] = b[j][i] = 1;
                }
            }
        }
    }
    
    build(b);
    return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:110:5: error: 'build' was not declared in this scope
  110 |     build(b);
      |     ^~~~~