Submission #778879

#	Time	Username	Problem	Language	Result	Execution time	Memory
778879		kingfran1907	The Big Prize (IOI17_prize)	C++14	90 / 100	86 ms	2888 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
#define X first
#define Y second

using namespace std;
typedef long long llint;
const int maxn = 2e5+10;

int l[maxn], r[maxn];
int out = -1;
int maxi = 0;

pair<int,int> query(int x) {
	if (l[x] != -1) return {l[x], r[x]};
	
	vector< int > v = ask(x);
	l[x] = v[0], r[x] = v[1];
	return {l[x], r[x]};
}

llint ra() {
	return (llint)rand() * rand() + rand() + rand();
}

void solve(int l, int r) {
	if (l > r) return;
	if (out != -1) return;
	if (query(l).X + query(l).Y == 0) {
		out = l;
		return;
	}
	if (query(l).X + query(l).Y < maxi) {solve(l + 1, r); return;}
	if (l == r) return;
	if (query(r).X + query(r).Y == 0) {
		out = r;
		return;
	}
	if (query(r).X + query(r).Y < maxi) {solve(l, r - 1); return;}
	if (query(l).X == query(r).X) return;
	
	int mid = (l + r) / 2;
	solve(l, mid);
	solve(mid + 1, r);
}

int find_best(int n) {
	memset(l, -1, sizeof l);
	//srand(31337);
	vector< int > v;
	for (int i = 0; i < n; i++) v.push_back(i);
	for (int i = 0; i < n; i++) 
		swap(v[i], v[ra() % n]);
	
	for (int i = 0; i < min(400, n); i++) {
		int x = v[i];
		pair<int, int> tr = query(x);
		if (tr.X + tr.Y == 0) return x;
		maxi = max(maxi, tr.X + tr.Y);
	}
	solve(0, n - 1);
	assert(out != -1);
	return out;
}

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