Submission #781184

#	Time	Username	Problem	Language	Result	Execution time	Memory
781184		Sam_a17	Radio Towers (IOI22_towers)	C++17	18 / 100	886 ms	6052 KiB

towers

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int)x.size()
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
 
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
 
// Indexed Set  
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
// template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(Tree <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
 
 
// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);
 
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if(str == "input") {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  } else if(str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
}

const int N = 2e5 + 10;
int a[N], mid = -1;
int f1 = 1, n;
vector<int> b;
int pi[N];

struct segTreeMax {
  vector<long long> mTree;
  int size;
 
  void init(long long n) {
    size = 1;
    while(size < n)  {
      size *= 2;
    }
    mTree.assign(2 * size - 1, 0);
  }
 
  void upd(int u, long long v, int x, int lx, int rx) { // set value at pos u
    if(rx - lx == 1) {
      mTree[x] = v;
      return;
    }
 
    int m = (lx + rx) / 2;
    if(u < m) {
      upd(u, v, 2 * x + 1, lx, m);
    }else {
      upd(u, v, 2 * x + 2, m, rx);
    }
    mTree[x] = max(mTree[2 * x + 1], mTree[2 * x + 2]);
  }
 
  void upd(int u, long long v) {
    upd(u, v, 0, 0, size);
  }
 
  long long qry (int l, int r, int x, int lx, int rx) { // range queries
    if(l >= rx || lx >= r) {
      return 0;
    }
    if(lx >= l && r >= rx) {
      return mTree[x];
    }
 
    int m = (rx + lx) / 2;
    long long s1 = qry(l, r, 2 * x + 1, lx, m);
    long long s2 = qry(l, r, 2 * x + 2, m, rx);
    return max(s1, s2);
  }
 
  long long qry(int l, int r) {
    if(l >= r) {
      return -10;
    } 
    return qry(l, r, 0, 0, size);
  }
};

segTreeMax seg_max, seg_all;

vector<int> ai;

void init(int maxN, std::vector<int> H) {
  n = maxN;
  pair<int, int> mx = {0, 0};

  seg_all.init(n + 1);
  for(int i = 0; i < n; i++) {
    a[i] = H[i];
    seg_all.upd(i, a[i]);
    mx = max(mx, make_pair(a[i], i));
  }
  
  vector<int> lowRig(n + 1, n), lowLef(n + 1, -1);
  stack<pair<int, int>> st;
  for(int i = 0; i < n; i++) {
    while(!st.empty() && st.top().first > a[i]) {
      int cur = st.top().second;
      lowRig[cur] = i;
      st.pop();
    }

    if(!st.empty()) {
      lowLef[i] = st.top().second;
    }
    st.push({a[i], i});
  }

  for(int i = 0; i < n; i++) {
    int curl = seg_all.qry(lowLef[i] + 1, i);
    if(i == 0) {
      curl = 2e9 + 10;
    }
    int curr = seg_all.qry(i + 1, lowRig[i]);
    if(i == n - 1) {
      curr = 2e9 + 10;
    }
    ai.push_back(min(curl, curr) - a[i]);
  }

  sort(all(ai));
  mid = mx.second;
  for(int i = 0; i < mid; i++) {
    if(a[i + 1] <= a[i]) {
      f1 = 0;
    }
  }

  for(int i = mid + 1; i < n; i++) {
    if(a[i] >= a[i - 1]) {
      f1 = 0;
    }
  }

  for(int i = 1; i < n - 1; i++) {
    pi[i] = pi[i - 1] + (a[i] > a[i - 1] && a[i] > a[i + 1]);
  }
  pi[n - 1] = pi[n - 2];
}

int max_towers(int L, int R, int D) {

  if(L == 0 && R == n - 1) {
    auto it = lower_bound(all(ai), D);
    int answ = 1;
    if(it != ai.end()) {
      int ind = it - ai.begin();
      answ = max(answ, n - ind);
    }
    // dbg(answ)
    return answ;
  }

  if(f1) {
    if(R <= mid || L >= mid) {
      return 1;
    }

    if(R - L + 1 == 1) {
      return 1;
    }

    if(a[mid] - D >= max(a[L], a[R])) {
      return 2;
    } else {
      return 1;
    }
  } else if(D == 1) {
    int cur = pi[R - 1] - pi[L] + 1;
    return max(1, cur);
  } else {
    vector<long long> dp(n + 1);
    long long answ = 0;

    set<pair<long long, long long>> ft;
    deque<pair<int, int>> vec;
    seg_max.init(n + 5);
    for(int i = L; i <= R; i++) {
      dp[i] = 1;

      auto it = lower_bound(all(vec), make_pair(a[i] + D, -1));
      if(it != vec.end()) {
        int ind = it - vec.begin();
        if(vec[ind].second >= 1) {
          dp[i] = max(dp[i], seg_max.qry(0, vec[ind].second) + 1);
        }
      }

      while (!vec.empty() && a[i] > vec.front().first) {
        vec.pop_front();
      }
      vec.push_front({a[i], i});

      while(!ft.empty() && ft.begin()->first <= a[i] - D) {
        seg_max.upd(ft.begin()->second, dp[ft.begin()->second]);
        ft.erase(ft.begin());
      }
      ft.insert({a[i], i});

      answ = max(answ, dp[i]);
    }
 
    return answ;
  }
}

Compilation message (stderr)

towers.cpp: In function 'void setIO(std::string)':
towers.cpp:76:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
towers.cpp:77:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   77 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
towers.cpp:79:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
towers.cpp:80:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 0 / 11
• Subtask 3: 0 / 12
• Subtask 4: 14 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23