Submission #778625

#	Time	Username	Problem	Language	Result	Execution time	Memory
778625		benjaminkleyn	The Big Prize (IOI17_prize)	C++17	90 / 100	84 ms	2056 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
#define mp make_pair

bool asked[200000] = {false};
int L[200000], R[200000];
int v, N;

bool Ask(int i)
{
    if (asked[i]) return L[i] + R[i] == 0;
    asked[i] = true;
    vector<int> res = ask(i);
    L[i] = res[0], R[i] = res[1];
    return L[i] + R[i] == 0;
}

int Find(int l, int r)
{
    if (Ask(l)) return l;
    while (l < r && L[l] + R[l] != L[v] + R[v])
        if (Ask(++l)) return l;

    if (Ask(r)) return r;
    while (l < r && L[r] + R[r] != L[v] + R[v])
        if (Ask(--r)) return r;

    int m = (l + r) / 2;
    if (Ask(m)) return m;
    if (L[r] - L[l] == 0) return -1;

    int x = Find(l, m);
    if (x >= 0) return x;

    int y = Find(m, r);
    if (y >= 0) return y;

    return -1;
}

int find_best(int n) 
{
    N = n, v = 0;
    for (int j = 0; j < n && j < 500; j++)
    {
        if (Ask(j)) return j;
        if (L[j] + R[j] > L[v] + R[v])
            v = j;
    }
    return Find(0, n - 1);
}

• Subtask 1: 20 / 20
• Subtask 2: 70 / 80