Submission #566330

#	Time	Username	Problem	Language	Result	Execution time	Memory
566330		lorenzoferrari	The Big Prize (IOI17_prize)	C++17	0 / 100	5 ms	304 KiB

prize

#include <bits/stdc++.h>
#include "prize.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template<typename K>
using ordered_set = tree
<K, null_type, less<K>,
rb_tree_tag,
tree_order_statistics_node_update
>;

int answer = -1;
int mx_cnt = 0;
ordered_set<int> found;
map<int, array<int, 2>> memo;

int found_in_range(int l, int r) {
  return found.order_of_key(r) - found.order_of_key(l);
}

array<int, 2> askme(int i) {
  array<int, 2> ans;
  if (memo.find(i) != memo.end()) {
    ans[0] = memo[i][0];
    ans[1] = memo[i][1];
  } else {
    auto v = ask(i);
    ans[0] = v[0];
    ans[1] = v[1];
  }
  memo[i] = {ans[0], ans[1]};
  if (ans[0] + ans[1]) found.insert(i);
  if (ans[0] + ans[1] == 0) answer = i;
  return ans;
}
inline int count(int i) { return askme(i)[0] + askme(i)[1]; }

void findall(int l, int r) {
  // assume t[l] = t[r] = v
  int cnt = askme(r)[0] - askme(l)[0];
  if (cnt <= found_in_range(l, r)) return;
  if (answer != -1) return;
  int m = (l + r) / 2;
  int lm = m, rm = m;
  while (count(lm) < count(l)) {
    if (answer != -1) return;
    --lm;
  }
  while (count(rm) != count(l)) {
    if (answer != -1) return;
    ++rm;
  }
  findall(l, lm);
  findall(rm, r);
}

int find_best(int n) {
  if (n <= 5000) {
    for (int i = 0; i < n; ++i) ask(i);
    return answer;
  }
  srand(time(NULL));
  for (int i = 0; i < 500; ++i) mx_cnt = max(mx_cnt, count(i));
  int l = 0; while (count(l) != mx_cnt) ++l;
  int r = n-1; while (count(r) != mx_cnt) --r;
  findall(l, r);
  return answer;
}

#ifdef LORENZO
int main() {
  cout << "insert n: "; fflush(stdout);
  int n; cin >> n;
  cout << "answer: " << find_best(n) << endl;
}
#endif

• Subtask 1: 0 / 20
• Subtask 2: 0 / 80