Submission #290318

#	Time	Username	Problem	Language	Result	Execution time	Memory
290318		A02	The Big Prize (IOI17_prize)	C++14	0 / 100	31 ms	22760 KiB

prize

#include <bits/stdc++.h>
#include "prize.h"

using namespace std;

vector<vector<int> > asked;

vector<int> ask2(int i){

    if (asked[i][0] == -1){
        asked[i] = ask(i);
    }

    return asked[i];

}

int find_best(int n) {

    asked = vector<vector<int> > (n, vector<int> (2, -1));

	if (n <= 5000){
        for (int i = 0; i < n; i++){
            vector<int> r = ask(i);
            if (r[0] == 0 && r[1] == 0){
                return i;
            }
        }
	}

    int small_count = 0;

    for (int i = 0; i < 500; i++){
        int low = 0;
        int high = n;
        for (int a = 0; a < 9; a++){
            small_count = max(small_count, ask2((low + high) / 2)[0] + ask2((low + high) / 2)[1]);
            if (i & (1 << 8)){
                low = (low + high) / 2;
            } else {
                high = (low + high) / 2;
            }
        }
    }

    vector<int> small_pos (small_count, -1);

    for (int p = 0; p < small_count; p++){
        //cout << 'p' << ' ' << p << endl;
        int low = 0;
        int high = n;
        int left_elements = 0;
        //pth small element in [0, n).

        while (high != low + 1){
            int mid = (low + high) / 2;
            //cout << low << ' ' << high << ' ' << left_elements << endl;
            while(ask2(mid)[0] + ask2(mid)[1] != small_count && mid - 1 >= low){
                mid--;
            }

            int m_original = (low + high) / 2;
            if (m_original != mid){
                if (ask2(mid)[0] + ask2(mid)[1] != small_count){
                    int width = m_original - low;
                    if (p <= left_elements + width){
                        high = m_original;
                    } else {
                        low = m_original;
                        left_elements += width;
                    }
                } else {
                    int extra = m_original - mid;
                    int left_of_mid_elements = ask2(m_original)[0] + extra - 1;
                    if (left_of_mid_elements >= p){
                        high = m_original;
                    } else {
                        low = m_original;
                        left_elements = left_of_mid_elements;
                    }
                }
            } else {
                int left_of_mid_elements = ask2(mid)[0];
                if (left_of_mid_elements >= p){
                    high = mid;
                } else {
                    low = mid;
                    left_elements = left_of_mid_elements;
                }
            }

        }

        small_pos[p] = low;
        if (ask2(low)[0] + ask2(low)[1] == 0){
            return low;
        }

    }
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:46:43: warning: control reaches end of non-void function [-Wreturn-type]
   46 |     vector<int> small_pos (small_count, -1);
      |                                           ^

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