Submission #1326299

#	Time	Username	Problem	Language	Result	Execution time	Memory
1326299		apxo	The Big Prize (IOI17_prize)	C++20	97.61 / 100	17 ms	4768 KiB

prize

#include "prize.h"
#include "bits/stdc++.h"
using namespace std;

#ifdef duc_debug
#include "bits/debug.h"
#else 
#define debug(...)
#endif


mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) {
  assert(l <= r);
  return uniform_int_distribution<int> (l, r)(rng);
}
const int maxn = 2e5 + 5;
const int B = 478;
vector<int> que[maxn];
int cnt_asks;

vector<int> abc(int i) {
  ++cnt_asks;
  if(!que[i].empty()) {
    return que[i];
  } else {
    return que[i] = ask(i);
  }
}

int ans, mx;

void calc(int l, int r) {
  if (r - l < 2 || ans != -1) return;
  if (que[r][0] - que[l][0] == 0) return;
  int mid = (l + r) >> 1;
  int pl = mid, pr = mid;
  bool skip_left = 0, skip_right = 0;
  while (pr < r) {
    abc(pr);
    if (que[pr][0] + que[pr][1] == 0) {
      ans = pr;
      return;
    }
    if (que[pr][0] == 0) skip_left = 1;
    if (que[pr][1] == 0) {
      skip_right = 1;
      break;
    }
    if (que[pr][0] + que[pr][1] == mx) break;
    ++pr;
  }
  
  if (!skip_right) {
    calc(pr, r);
  }
  
  if (skip_left) return;
  while (pl > l) {
    abc(pl);
    if (que[pl][0] + que[pl][1] == 0) {
      ans = pl;
      return;
    }
    if (que[pl][0] == 0) {
      skip_left = 1;
      break;
    }
    if (que[pl][0] + que[pl][1] == mx) break;
    --pl;
  }
  if (!skip_left) {
    calc(l, pl);
  }
}

int find_best(int n) {
  ans = -1;
  int x = min(n - 1, B);
  for (int i = 0; i <= x; ++i) {
    vector<int> cur = abc(i);
    if (cur[0] + cur[1] == 0) return i;
    mx = max(mx, cur[0] + cur[1]);
  }
  while (x >= 0) {
    if (que[x][0] + que[x][1] == mx) break;
    --x;
  }
  int lst = n - 1;
  while (lst >= 0) {
    vector<int> cur = abc(lst);
    if (cur[0] + cur[1] == 0) return lst;
    if (cur[0] + cur[1] == mx) break;
    --lst;
  }
  calc(x, lst);
  return ans;
}

• Subtask 1: 20 / 20
• Subtask 2: 77.61 / 80