Submission #102763

#	Time	Username	Problem	Language	Result	Execution time	Memory
102763		bert30702	The Big Prize (IOI17_prize)	C++17	100 / 100	49 ms	708 KiB

prize

#include <bits/stdc++.h>
#include "prize.h"
#define pii pair<int, int>
#define F first
#define S second
using namespace std;
//vector<int> ask(int p) {
//	// cout << p << endl;
//	int a = 0, b = 0; 
//	int v[] = {3, 2, 3, 1, 3, 3, 2, 3};
//	for(int i =     0; i < p; i ++) a += (v[i] < v[p]);
//	for(int i = p + 1; i < 8; i ++) b += (v[i] < v[p]);
//	return {a, b};
//}
unordered_map<int, pii> mp;
pii query(int p) {
	if(mp.find(p) != mp.end()) return mp[p];
	vector<int> v = ask(p);
	return mp[p] = {v[0], v[1]};
}
vector<pii> ans;
void dfs(int l, int r, pii a, pii b, int mx) {
	// cout << l << ' ' << r << endl;
	if(l == r) {
		if(b.F + b.S != mx) ans.push_back({b.F + b.S, l});
		return;
	}
	if(a == b) return;
	int m = l + r >> 1;
	pii v = query(m);
	if(v.F + v.S != mx) {
		ans.push_back({v.F + v.S, m});
		if(m != l) dfs(l, m - 1, a, query(m - 1), mx);
		if(m != r) dfs(m + 1, r, query(m + 1), b, mx);
	}
	else {
		if(v == a) return dfs(m + 1, r, v, b, mx);
		if(v == b) return dfs(    l, m, a, v, mx);
		dfs(    l, m, a, v, mx);
		dfs(m + 1, r, v, b, mx);
	}
}
int find_best(int n) {
	srand(time(0));
	int mx = 0;
	for(int i = 0; i < 10; i ++) {
		pii tmp = query(rand() % n);
		mx = max(mx, tmp.F + tmp.S);
	}
	dfs(0, n - 1, query(0), query(n - 1), mx);
	pii mn = {mx, -1};
	// for(auto it: ans) cout << it.S << ' '; cout << endl;
	for(auto it: ans) mn = min(mn, it);
	return mn.S;
}
//main () {
//	cout << find_best(8);
//}

Compilation message (stderr)

prize.cpp: In function 'void dfs(int, int, std::pair<int, int>, std::pair<int, int>, int)':
prize.cpp:29:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int m = l + r >> 1;
          ~~^~~

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