Submission #379493

#	Time	Username	Problem	Language	Result	Execution time	Memory
379493		SuhaibSawalha1	Connecting Supertrees (IOI20_supertrees)	C++14	40 / 100	278 ms	24300 KiB

supertrees

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

vector<int> dsu, sz;

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

bool unite (int u, int v) {
  if ((u = find(u)) != (v = find(v))) {
    if (sz[u] < sz[v]) {
      swap(u, v);
    }
    dsu[v] = u;
    sz[u] += sz[v];
    return 1;
  }
  return 0;
}
    
int construct(vector<vector<int>> p) {
  int n = p.size();
  dsu.resize(n);
  iota(dsu.begin(), dsu.end(), 0);
  sz.resize(n, 1);
  vector<vector<int>> ans(n, vector<int>(n));
  bool two = 0;
  auto sit = [&] (int i, int j, int t) {
    ans[i][j] = ans[j][i] = t;
  };
  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      if (p[i][j] == 1) {
        sit(i, j, unite(i, j));
      }
      if (p[i][j] == 2) {
        two = 1;
        unite(i, j);
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (p[i][j] == 0 && find(i) == find(j)) {
        return 0;
      }
    }
  }
  if (two) {
    vector<vector<int>> c(n);
    for (int i = 0; i < n; ++i) {
      c[find(i)].push_back(i);
    }
    for (int i = 0; i < n; ++i) {
      if (c[i].size() >= 2) {
        if (c[i].size() == 2) {
          return 0;
        }
        sit(c[i][0], c[i][1], 1);
        sit(c[i][1], c[i][2], 1);
        for (int j = 3; j < c[i].size(); ++j) {
          sit(c[i][j], c[i][j - 1], 1);
        }
        sit(c[i].back(), c[i][0], 1);
      }
    }
  }
  build(ans);
  return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:63:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |         for (int j = 3; j < c[i].size(); ++j) {
      |                         ~~^~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 10 / 10
• Subtask 3: 19 / 19
• Subtask 4: 0 / 35
• Subtask 5: 0 / 21
• Subtask 6: 0 / 4