Submission #549344

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
549344	2022-04-15T15:48:26 Z	cig32	The Big Prize (IOI17_prize)	C++17	99.32 / 100	44 ms	1908 KB

prize

#include "prize.h"
 
 
 
 
#include <iostream>
#include <vector>
#include <algorithm>
#include "bits/stdc++.h"
 
using namespace std;
 
int find_best(int n);
std::vector<int> ask(int i);
 
static const int max_q = 5000;
static int n;
static int query_count = 0;
static vector<int> g;
static vector<vector<int> > rank_count;
 
 
 
mt19937 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
 
int find_best(int n) {
  
  if(n <= 5000) {
    for(int i=0; i<n; i++) {
      vector<int> res = ask(i);
      if(res[0] + res[1] == 0) {
        return i;
      }
    }
  }
  int res[n][2];
  for(int i=0; i<n; i++) {
    for(int j=0; j<2; j++) {
      res[i][j] = -1;
    }
  }
  int t = ceil(sqrt(n));
  vector<int> v;
  int goodcnt = 0;
  for(int i=0; i<t; i++) {
    int x;
    
    x = t * i + (t - 1);
    if(x >= n) {
      
      while(1) {
        x = rnd(0, n - 1);
        if(res[x][0] == -1) break;
      }
 
    }
    vector<int> ok = ask(x);
    goodcnt = max(goodcnt, ok[0] + ok[1]);
    res[x][0] = ok[0], res[x][1] = ok[1];
    if(ok[0] + ok[1] == 0) {
      return x;
    }
    //cout << ok[0] + ok[1] << " ";
  }
  //cout << "\n";
  //cout << goodcnt << "\n";
  // solution idea: binary search
  // find all 'good' indices, one of them holds the big prize
  // 450 * log2(450) + C queries?
  vector<int> big;
  for(int i=0; i<n; i++) {
    if(res[i][0] != -1 && res[i][0] + res[i][1] == goodcnt) {
      big.push_back(i);
      //cout << i << " ";
    }
  }
  //cout << "\n";
  //cout << big.size() << "\n";
  queue<pair<pair<int, int>, int> > ranges;
  if(big[0] != 0 && res[big[0]][0] > 0) ranges.push({{0, big[0] - 1}, res[big[0]][0]});
  for(int i=1; i<big.size(); i++) {
    if(big[i-1] + 1 == big[i]) continue;
    if(res[big[i]][0] - res[big[i-1]][0] > 0) ranges.push({{big[i-1] + 1, big[i] - 1}, res[big[i]][0] - res[big[i-1]][0]});
  }
  if(big[big.size() - 1] != n - 1 && res[big[big.size() - 1]][1] > 0) ranges.push({{big[big.size() - 1] + 1, n - 1}, res[big[big.size() - 1]][1]});
  //cout << ranges.size() << "\n";
  while(ranges.size()) {
    pair<pair<int, int>, int> f = ranges.front();
    //cout << "split ["  << f.first.first <<", "<<f.first.second <<"]: " <<f.second << "\n";
    ranges.pop();
    if(f.second * 1.1 >= f.first.second - f.first.first + 1) {
      // just query each one, at most 2 * 450 here
      for(int i = f.first.first; i <= f.first.second; i++) {
        vector<int> qwq = ask(i);
        if(qwq[0] + qwq[1] == 0) return i;
      }
    }
    else {
      int mid = (f.first.first + f.first.second) >> 1;
      vector<int> qwq;
      while(1) {
        if(res[mid][0] == -1) {
          qwq = ask(mid);
          res[mid][0] = qwq[0];
          res[mid][1] = qwq[1];
          if(qwq[0] + qwq[1] == 0) return mid;
          if(qwq[0] + qwq[1] == goodcnt) break;
        }
        mid = rnd(f.first.first, f.first.second);
      }
      /*
      cout << "lchild " <<(f.first.first == 0 ? 0 : res[f.first.first - 1][0]) << ", ";
      cout << "rchild "<<(f.first.second == n - 1 ? 0 : res[f.first.second + 1][1])<<"\n";
      cout << "results "<<qwq[0] <<" " <<qwq[1] << "\n";
      */
      if(f.first.first <= mid - 1 && qwq[0] - (f.first.first == 0 ? 0 : res[f.first.first - 1][0]) > 0) {
        ranges.push({{f.first.first, mid - 1}, qwq[0] - (f.first.first == 0 ? 0 : res[f.first.first - 1][0])});
      }
      if(mid + 1 <= f.first.second && qwq[1] - (f.first.second == n - 1 ? 0 : res[f.first.second + 1][1]) > 0) {
        ranges.push({{mid + 1, f.first.second}, qwq[1] - (f.first.second == n - 1 ? 0 : res[f.first.second + 1][1])});
      }
    }
  }
}

Compilation message

prize.cpp: In function 'int find_best(int)':
prize.cpp:84:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |   for(int i=1; i<big.size(); i++) {
      |                ~^~~~~~~~~~~
prize.cpp:46:15: warning: control reaches end of non-void function [-Wreturn-type]
   46 |   vector<int> v;
      |               ^
prize.cpp: At global scope:
prize.cpp:18:12: warning: 'query_count' defined but not used [-Wunused-variable]
   18 | static int query_count = 0;
      |            ^~~~~~~~~~~
prize.cpp:17:12: warning: 'n' defined but not used [-Wunused-variable]
   17 | static int n;
      |            ^

Subtask #1

20.0 / 20.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	4 ms	1744 KB	Output is correct
2	Correct	6 ms	1832 KB	Output is correct
3	Correct	3 ms	1896 KB	Output is correct
4	Correct	3 ms	1848 KB	Output is correct
5	Correct	4 ms	1908 KB	Output is correct
6	Correct	6 ms	1832 KB	Output is correct
7	Correct	6 ms	1744 KB	Output is correct
8	Correct	6 ms	1828 KB	Output is correct
9	Correct	3 ms	1872 KB	Output is correct
10	Correct	6 ms	1872 KB	Output is correct

Subtask #2

79.32 / 80.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	4 ms	1832 KB	Output is correct
2	Correct	6 ms	1828 KB	Output is correct
3	Correct	4 ms	1868 KB	Output is correct
4	Correct	5 ms	1828 KB	Output is correct
5	Correct	7 ms	1820 KB	Output is correct
6	Correct	6 ms	1824 KB	Output is correct
7	Correct	5 ms	1744 KB	Output is correct
8	Correct	3 ms	1868 KB	Output is correct
9	Correct	4 ms	1832 KB	Output is correct
10	Correct	8 ms	1868 KB	Output is correct
11	Correct	7 ms	1744 KB	Output is correct
12	Correct	6 ms	1736 KB	Output is correct
13	Correct	7 ms	1824 KB	Output is correct
14	Correct	8 ms	464 KB	Output is correct
15	Correct	30 ms	1872 KB	Output is correct
16	Correct	40 ms	1864 KB	Output is correct
17	Correct	31 ms	1824 KB	Output is correct
18	Correct	38 ms	1736 KB	Output is correct
19	Correct	27 ms	1836 KB	Output is correct
20	Correct	22 ms	1060 KB	Output is correct
21	Correct	29 ms	1836 KB	Output is correct
22	Correct	30 ms	1828 KB	Output is correct
23	Correct	6 ms	1736 KB	Output is correct
24	Correct	8 ms	1832 KB	Output is correct
25	Correct	31 ms	1736 KB	Output is correct
26	Correct	17 ms	1852 KB	Output is correct
27	Correct	5 ms	1744 KB	Output is correct
28	Correct	34 ms	1840 KB	Output is correct
29	Correct	31 ms	1856 KB	Output is correct
30	Correct	22 ms	1868 KB	Output is correct
31	Correct	38 ms	1832 KB	Output is correct
32	Correct	7 ms	1824 KB	Output is correct
33	Correct	0 ms	208 KB	Output is correct
34	Correct	39 ms	1828 KB	Output is correct
35	Correct	7 ms	1828 KB	Output is correct
36	Correct	40 ms	1824 KB	Output is correct
37	Correct	5 ms	1744 KB	Output is correct
38	Correct	4 ms	1860 KB	Output is correct
39	Correct	28 ms	1832 KB	Output is correct
40	Correct	38 ms	1872 KB	Output is correct
41	Correct	44 ms	1832 KB	Output is correct
42	Correct	21 ms	1848 KB	Output is correct
43	Correct	27 ms	1744 KB	Output is correct
44	Correct	35 ms	1840 KB	Output is correct
45	Correct	26 ms	1744 KB	Output is correct
46	Correct	36 ms	1860 KB	Output is correct
47	Correct	26 ms	1808 KB	Output is correct
48	Correct	24 ms	1736 KB	Output is correct
49	Correct	43 ms	1848 KB	Output is correct
50	Correct	39 ms	1832 KB	Output is correct
51	Correct	40 ms	1872 KB	Output is correct
52	Correct	34 ms	1828 KB	Output is correct
53	Correct	8 ms	1816 KB	Output is correct
54	Correct	18 ms	1844 KB	Output is correct
55	Correct	31 ms	1736 KB	Output is correct
56	Correct	37 ms	1744 KB	Output is correct
57	Correct	39 ms	1832 KB	Output is correct
58	Correct	36 ms	1744 KB	Output is correct
59	Correct	36 ms	1744 KB	Output is correct
60	Correct	37 ms	1820 KB	Output is correct
61	Correct	5 ms	1864 KB	Output is correct
62	Correct	6 ms	1744 KB	Output is correct
63	Correct	5 ms	1820 KB	Output is correct
64	Correct	7 ms	1828 KB	Output is correct
65	Correct	4 ms	1744 KB	Output is correct
66	Correct	12 ms	1852 KB	Output is correct
67	Correct	5 ms	1868 KB	Output is correct
68	Correct	9 ms	1832 KB	Output is correct
69	Correct	7 ms	1844 KB	Output is correct
70	Correct	5 ms	1828 KB	Output is correct
71	Correct	34 ms	1864 KB	Output is correct
72	Correct	5 ms	1868 KB	Output is correct
73	Correct	34 ms	1868 KB	Output is correct
74	Correct	39 ms	1872 KB	Output is correct
75	Correct	8 ms	1872 KB	Output is correct
76	Correct	35 ms	1872 KB	Output is correct
77	Correct	38 ms	1872 KB	Output is correct
78	Correct	8 ms	1864 KB	Output is correct
79	Correct	26 ms	1744 KB	Output is correct
80	Correct	34 ms	1872 KB	Output is correct
81	Correct	37 ms	1872 KB	Output is correct
82	Correct	41 ms	1868 KB	Output is correct
83	Correct	7 ms	1744 KB	Output is correct
84	Correct	27 ms	1868 KB	Output is correct
85	Correct	33 ms	1872 KB	Output is correct
86	Correct	11 ms	1864 KB	Output is correct
87	Correct	7 ms	1744 KB	Output is correct
88	Correct	8 ms	1744 KB	Output is correct
89	Correct	10 ms	1868 KB	Output is correct
90	Correct	5 ms	1872 KB	Output is correct
91	Correct	10 ms	1828 KB	Output is correct
92	Correct	8 ms	1868 KB	Output is correct
93	Partially correct	38 ms	1864 KB	Partially correct - number of queries: 5068
94	Partially correct	42 ms	1744 KB	Partially correct - number of queries: 5055
95	Correct	31 ms	1872 KB	Output is correct
96	Correct	40 ms	1864 KB	Output is correct
97	Correct	30 ms	1860 KB	Output is correct