Submission #70313

#	Time	Username	Problem	Language	Result	Execution time	Memory
70313		E869120	The Big Prize (IOI17_prize)	C++14	20 / 100	86 ms	572 KiB

prize

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

int find_best(int n) {
	int cx = 0;
	
	while (true) {
		vector<int> X1 = ask(n - 1 - cx);
		
		int L = cx, R = n, M, maxn = 0, QQ = 18;
		
		vector<int> G = {511, 1023, 4095};
		for (int i = 0; i < G.size(); i++) {
			vector<int> X2 = ask(min(n - 1, cx + G[i]));
			if (X2 != X1) { R = min(n, cx + G[i]); break; }
		}
		
		for (int i = 0; i <= 18; i++) { if ((1 << i) >= R - L + 1) { QQ = i; break; } }
		
		for (int i = 0; i < QQ; i++) {
			M = (L + R) / 2;
			vector<int> R1 = ask(n - 1 - min(n - 1, M));
			if (R1[0] + R1[1] == 0) return n - 1 - M;
			if (X1 == R1) { L = M; maxn = max(maxn, M); }
			else { R = M; }
		}
		cx = maxn + 2;
	}
	return -1;
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:14:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < G.size(); i++) {
                   ~~^~~~~~~~~~

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