Submission #736242

#	Time	Username	Problem	Language	Result	Execution time	Memory
736242		math_rabbit_1028	Radio Towers (IOI22_towers)	C++17	0 / 100	695 ms	56368 KiB

towers

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

int n;
vector<int> arr;
vector<int> upidx, downidx, revupidx;

struct localmax {
  int idx, d, l, r;
  bool operator<(const localmax &other) const {
    if (d == other.d) return idx < other.idx;
    return d < other.d;
  }
  void update() {
    d = arr[upidx[idx]] - max(arr[l], arr[r]);
  } 
} local_value[101010];
int adj[101010][2];
set<localmax> local;

vector< pair<int, int> > Dlist;

struct Node {
  Node *lt, *rt;
  int val;
  Node() {
    lt = rt = NULL;
    val = 0;
  }
};
Node *root[101010];
int first[101010];

void build(Node *node, int st, int ed) {
  if (st == ed) {
    node->val = first[st];
    return;
  }
  int mid = (st + ed) / 2;
  node->lt = new Node();
  node->rt = new Node();
  build(node->lt, st, mid);
  build(node->rt, mid + 1, ed);
  node->val = node->lt->val + node->rt->val;
}

void update(Node *prev, Node *now, int st, int ed, int idx, int value) {
  if (st == ed) {
    now->val = value;
    return;
  }
  int mid = (st + ed) / 2;
  if (idx <= mid) {
    now->lt = new Node();
    now->rt = prev->rt;
    update(prev->lt, now->lt, st, mid, idx, value);
  }
  else {
    now->lt = prev->lt;
    now->rt = new Node();
    update(prev->rt, now->rt, mid + 1, ed, idx, value);
  }
  now->val = now->lt->val + now->rt->val;
}

int get(Node *node, int st, int ed, int gs, int ge) {
  if (st > ge || ed < gs) return 0;
  if (gs <= st && ed <= ge) return node->val;
  int mid = (st + ed) / 2;
  return get(node->lt, st, mid, gs, ge) + get(node->rt, mid + 1, ed, gs, ge);
}

void init(int N, vector<int> H) {
  n = N;
  for (int i = 0; i < n; i++) arr.push_back(H[i]);
  
  if (arr[0] < arr[1]) downidx.push_back(0);
  for (int i = 1; i < n - 1; i++) {
    if (arr[i] > arr[i - 1] && arr[i] > arr[i + 1]) upidx.push_back(i);
    if (arr[i] < arr[i - 1] && arr[i] < arr[i + 1]) downidx.push_back(i);
  }
  if (arr[n - 1] < arr[n - 2]) downidx.push_back(n - 1);

  for (int i = 0; i < upidx.size(); i++) {
    local_value[i] = {i, 0, downidx[i], downidx[i + 1]};
    local_value[i].update();
    local.insert(local_value[i]);
    adj[i][0] = i - 1;
    adj[i][1] = i + 1;
  }

  while (!local.empty()) {
    localmax now = *local.begin();
    Dlist.push_back({now.d, upidx[now.idx]});
    int next = (arr[now.l] < arr[now.r] ? now.l : now.r);
    local.erase(local.begin());
    if (adj[now.idx][0] >= 0) {
      set<localmax>::iterator iter = local.find(local_value[adj[now.idx][0]]);
      if (iter != local.end()) {
        local.erase(iter);
        local_value[adj[now.idx][0]].r = next;
        local_value[adj[now.idx][0]].update();
        local.insert(local_value[adj[now.idx][0]]);
        adj[adj[now.idx][0]][1] = adj[now.idx][1];
      }
    }
    if (adj[now.idx][1] < upidx.size()) {
      set<localmax>::iterator iter = local.find(local_value[adj[now.idx][1]]);
      if (iter != local.end()) {
        local.erase(iter);
        local_value[adj[now.idx][1]].l = next;
        local_value[adj[now.idx][1]].update();
        local.insert(local_value[adj[now.idx][1]]);
        adj[adj[now.idx][1]][0] = adj[now.idx][0];
      }
    }
  }

  for (int i = 0; i < upidx.size(); i++) first[upidx[i]] = 1;

  root[0] = new Node();
  build(root[0], 0, n - 1);
  for (int i = 0; i < Dlist.size(); i++) {
    root[i + 1] = new Node();
    update(root[i], root[i + 1], 0, n - 1, Dlist[i].second, 0);
  }

  for (int i = 0; i < upidx.size(); i++) revupidx.push_back(-upidx[i]);
  sort(revupidx.begin(), revupidx.end());

}

int max_towers(int L, int R, int D) {
  int d = lower_bound(Dlist.begin(), Dlist.end(), make_pair(D, 0)) - Dlist.begin();
  int ans = get(root[d], 0, n - 1, L, R) + 1;
  if (arr[L] < arr[L + 1]) {
    int near = lower_bound(upidx.begin(), upidx.end(), L) - upidx.begin();
    if (arr[upidx[near]] < arr[L] + D) ans--;
  }
  if (arr[R] < arr[R - 1]) {
    int near = lower_bound(revupidx.begin(), revupidx.end(), -R) - revupidx.begin();
    if (arr[upidx[-near]] < arr[R] + D) ans--;
  }
  return ans;
}

Compilation message (stderr)

towers.cpp: In function 'void init(int, std::vector<int>)':
towers.cpp:85:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |   for (int i = 0; i < upidx.size(); i++) {
      |                   ~~^~~~~~~~~~~~~~
towers.cpp:108:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  108 |     if (adj[now.idx][1] < upidx.size()) {
      |         ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
towers.cpp:120:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |   for (int i = 0; i < upidx.size(); i++) first[upidx[i]] = 1;
      |                   ~~^~~~~~~~~~~~~~
towers.cpp:124:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  124 |   for (int i = 0; i < Dlist.size(); i++) {
      |                   ~~^~~~~~~~~~~~~~
towers.cpp:129:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  129 |   for (int i = 0; i < upidx.size(); i++) revupidx.push_back(-upidx[i]);
      |                   ~~^~~~~~~~~~~~~~

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