Submission #379532

#	Time	Username	Problem	Language	Result	Execution time	Memory
379532		SuhaibSawalha1	Connecting Supertrees (IOI20_supertrees)	C++14	96 / 100	287 ms	22376 KiB

supertrees

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

struct DSU {

  vector<int> dsu, sz;

  DSU (int n) {
    dsu.resize(n);
    iota(dsu.begin(), dsu.end(), 0);
    sz.resize(n, 1);
  }

  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();
  for (int i = 0; i < n; ++i) {
    if (count(p[i].begin(), p[i].end(), 2) && count(p[i].begin(), p[i].end(), 3)) {
      return 0;
    }
  }
  vector<vector<int>> ans(n, vector<int>(n));
  DSU nodes(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, nodes.unite(i, j));
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      if (p[i][j] == 0 && nodes.find(i) == nodes.find(j)) {
        return 0;
      }
    }
  }
  vector<vector<int>> c(n);
  for (int i = 0; i < n; ++i) {
    c[nodes.find(i)].push_back(i);
  }
  auto Do = [&] (int e) {
    DSU cmp(n);
    for (int i = 0; i < n; ++i) {
      for (int j = 0; j < n; ++j) {
        if (p[i][j] == e) {
          cmp.unite(nodes.find(i), nodes.find(j));
        }
      }
    }
    vector<vector<int>> C(n);
    for (int i = 0; i < n; ++i) {
      C[cmp.find(i)].push_back(i);
    }
    for (int i = 0; i < n; ++i) {
      if (i != cmp.find(i)) {
        continue;
      }
      for (int j = 0; j < n; ++j) {
        if (nodes.find(i) != nodes.find(j) && cmp.find(i) == cmp.find(j) && p[i][j] != e) {
          return 0;
        }
      }
      for (int j : c[i]) {
        for (int k = 0; k < n; ++k) {
          if ((p[k][i] == e) ^ (p[j][k] == e)) {
            return 0;
          }
        }
      }
      for (int j = 0; j < C[i].size(); ++j) {
        for (int k = j + 1; k < C[i].size(); ++k) {
          if (p[C[i][j]][C[i][k]] ^ e) {
            return 0;
          }
        }
      }
      if (C[i].size() > 1 && C[i].size() <= e) {
        return 0;
      }
      if (C[i].size() > e) {
        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);
        if (e == 3) {
          sit(C[i][1], C[i][3], 1);
        }
      }
    }
    return 1;
  };
  if (!Do(2) || !Do(3)) {
    return 0;
  }
  build(ans);
  return 1;
}

Compilation message (stderr)

supertrees.cpp: In lambda function:
supertrees.cpp:92:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |       for (int j = 0; j < C[i].size(); ++j) {
      |                       ~~^~~~~~~~~~~~~
supertrees.cpp:93:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |         for (int k = j + 1; k < C[i].size(); ++k) {
      |                             ~~^~~~~~~~~~~~~
supertrees.cpp:99:42: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   99 |       if (C[i].size() > 1 && C[i].size() <= e) {
      |                              ~~~~~~~~~~~~^~~~
supertrees.cpp:102:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  102 |       if (C[i].size() > e) {
      |           ~~~~~~~~~~~~^~~
supertrees.cpp:105:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  105 |         for (int j = 3; j < C[i].size(); ++j) {
      |                         ~~^~~~~~~~~~~~~
supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:41:8: warning: unused variable 'two' [-Wunused-variable]
   41 |   bool two = 0;
      |        ^~~

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