Submission #993959

#	Time	Username	Problem	Language	Result	Execution time	Memory
993959		MilosMilutinovic	September (APIO24_september)	C++17	100 / 100	282 ms	22740 KiB

september

#include "september.h"
#include <bits/stdc++.h>

using namespace std;

int solve(int n, int m, vector<int> par, vector<vector<int>> s) {
  vector<int> p(n);
  iota(p.begin(), p.end(), 0);
  vector<int> from(n, n), to(n, 0);
  function<int(int)> GetPar = [&](int x) {
    return p[x] == x ? x : p[x] = GetPar(p[x]);
  };
  auto Merge = [&](int x, int y) {
    x = GetPar(x);
    y = GetPar(y);
    if (x == y) {
      return;
    }
    from[x] = min(from[x], from[y]);
    to[x] = max(to[x], to[y]);
    p[y] = x;
  };
  for (int i = 0; i < m; i++) {
    for (int j = 0; j + 1 < n; j++) {
      from[s[i][j]] = min(from[s[i][j]], j);
      to[s[i][j]] = max(to[s[i][j]], j);
    }
  }
  vector<vector<int>> g(n);
  for (int i = 1; i < n; i++) {
    g[par[i]].push_back(i);
  }
  int T = 0;
  vector<int> dfn(n);
  vector<int> dfo(n);
  function<void(int)> Dfs = [&](int v) {
    dfn[v] = ++T;
    for (int u : g[v]) {
      Dfs(u);
    }
    dfo[v] = ++T; 
  };  
  Dfs(0);
  auto IsAnc = [&](int x, int y) {
    return dfn[x] <= dfn[y] && dfo[y] <= dfo[x];
  };
  for (int k = 0; k < m; k++) {
    vector<int> pos(n);
    for (int i = 0; i + 1 < n; i++) {
      pos[s[k][i]] = i;
    }
    pos[0] = n;
    auto up = pos;
    function<void(int)> Dfs = [&](int v) {
      for (int u : g[v]) {
        up[u] = min(up[u], up[v]);
        Dfs(u);
      }
    };
    Dfs(0);
    vector<int> mx(n);
    iota(mx.begin(), mx.end(), 0);
    for (int i = 1; i < n; i++) {
      mx[up[i]] = max(mx[up[i]], pos[i]);
    }
    for (int i = 0; i + 1 < n; i++) {
      if (i > 0) {
        mx[i] = max(mx[i], mx[i - 1]);
      }
      if (mx[i] > i) {
        Merge(s[k][i], s[k][i + 1]);
      }
    }
  }
  vector<pair<int, int>> ev;
  for (int i = 1; i < n; i++) {
    if (GetPar(i) != i) {
      continue;
    }
    ev.emplace_back(from[i], ~to[i]);
    ev.emplace_back(to[i], to[i]);
  }
  sort(ev.begin(), ev.end());
  multiset<int> st;
  int res = 0;
  for (auto& p : ev) {
    if (st.empty()) {
      res += 1;
    }
    int v = p.second;
    if (v < 0) {
      st.insert(~v);
    } else {
      st.erase(st.find(v));
    }
  }
  return res;
}

Compilation message (stderr)

september.cpp: In function 'int solve(int, int, std::vector<int>, std::vector<std::vector<int> >)':
september.cpp:44:8: warning: variable 'IsAnc' set but not used [-Wunused-but-set-variable]
   44 |   auto IsAnc = [&](int x, int y) {
      |        ^~~~~

• Subtask 1: 11 / 11
• Subtask 2: 14 / 14
• Subtask 3: 5 / 5
• Subtask 4: 9 / 9
• Subtask 5: 5 / 5
• Subtask 6: 11 / 11
• Subtask 7: 9 / 9
• Subtask 8: 11 / 11
• Subtask 9: 9 / 9
• Subtask 10: 16 / 16