Submission #699419

#	Time	Username	Problem	Language	Result	Execution time	Memory
699419		MasterTaster	The Big Prize (IOI17_prize)	C++14	90 / 100	63 ms	2108 KiB

prize

#include "prize.h"
#include <iostream>
#include <vector>
#include <cmath>

#define ll long long
#define pii pair<int, int>
#define xx first
#define yy second
#define pb push_back
#define MAXN 200010

using namespace std;

int n, l[MAXN], r[MAXN], maxx, ret=-1, sq=490;
vector<int> all;

/*bool check(int i, int k)
{
    vector<int> p=ask(i);
    int le=p[0], ri=p[1];
    if ((le+ri)<maxx) return true;
    if (le>k) return true;
    return false;
}*/

bool vis[MAXN];
void askk(int i)
{
    if (i==-1) return;
    if (i==n) { l[i]=maxx; return; }
    if (!vis[i]) { vector<int> p=ask(i); l[i]=p[0]; r[i]=p[1]; vis[i]=true; }
}
void ch()
{
    askk(all[all.size()-1]);
    if ((l[all[all.size()-1]]+r[all[all.size()-1]])==0) ret=all[all.size()-1];
}

void solve(int left, int right)
{
    if (ret!=-1) return;
    int mid=left+(right-left)/2;
    askk(mid); askk(left-1); askk(right+1);

    if (left>right) return;
    if (left==right) { if ((l[mid]+r[mid])<maxx) all.pb(mid); ch(); return; }
    if (left==(right-1))
    {
        if ((l[mid]+r[mid])<maxx) { all.pb(mid); ch(); }
        mid++;
        askk(mid);
        if ((l[mid]+r[mid])<maxx) { all.pb(mid); ch(); }
        return;
    }

    if ((l[mid]+r[mid])<maxx) { all.pb(mid); ch(); if (ret!=-1) return; solve(left, mid-1); solve(mid+1, right); }
    else
    {
        if (l[mid]-l[left-1]) solve(left, mid-1);
        if (l[right+1]-l[mid]) solve(mid+1, right);
    }
}

int find_best(int N) {
    n=N;
    sq=min(2*sq, n-1);//2*sqrt(n);
    for (int i=0; i<=sq; i++)
    {
        askk(i);
        if (l[i]+r[i]==0) return i;
        maxx=max(maxx, l[i]+r[i]);
    }

    int left=0, right=n-1;
    solve(left, right);

    int ret=0;
    for (int i=0; i<all.size(); i++) { /*askk(all[i]);*/ if ((l[all[i]]+r[all[i]])==0) ret=all[i]; }
    return ret;
}
///1, 2, 5, 26, 677
/*
8
3 2 3 1 3 3 2 3
*/

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:79:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |     for (int i=0; i<all.size(); i++) { /*askk(all[i]);*/ if ((l[all[i]]+r[all[i]])==0) ret=all[i]; }
      |                   ~^~~~~~~~~~~

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