Submission #828091

#	Time	Username	Problem	Language	Result	Execution time	Memory
828091		tranxuanbach	The Big Prize (IOI17_prize)	C++17	90 / 100	74 ms	9400 KiB

prize

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

const int N = 2e5 + 5;

struct fenwick_tree{
	int fen[N];
	bool account[N];

	void update(int i){
		account[i] = true;
		i++;
		for (; i < N; i += i & -i){
			fen[i]++;
		}
	}

	int query(int i){
		i++;
		int ans = 0;
		for (; i > 0; i -= i & -i){
			ans += fen[i];
		}
		return ans;
	}

	int query(int l, int r){
		return query(r) - query(l - 1);
	}
} fen;

int n;
vector <int> query_answer[N];
int cnt_left[N], cnt_right[N];
int type[N];

void query(int x){
	if (not query_answer[x].empty()){
		return;
	}
	query_answer[x] = ask(x);
	cnt_left[x] = query_answer[x].front();
	cnt_right[x] = query_answer[x].back();
	type[x] = accumulate(query_answer[x].begin(), query_answer[x].end(), 0);
}

int find_min_lollipop(){
	int lo = 1, hi = n - 1;
	while (lo < hi){
		int mid = (lo + hi) >> 1;
		int sum = 0, t = mid;
		while (t){
			sum += t;
			t = sqrt(t - 1);
		}
		if (sum >= n){
			hi = mid;
		}
		else{
			lo = mid + 1;
		}
	}
	return lo;
}

int type_lollipop;
int jump_right[N];
int global_hi;

int search_important(int l, int r){
	if (l > r){
		exit(0);
	}
	if (l == r){
		query(l);
		fen.update(l);
		return l;
	}
	int mid = (l + r) >> 1;
	query(mid);
	if (type[mid] == type_lollipop){
		if (fen.query(mid + 1, n - 1) != cnt_right[mid]){
			return search_important(mid + 1, r);
		}
		else{
			global_hi = min(global_hi, mid - 1);
			return search_important(l, mid - 1);
		}
		return -1;
	}
	if (not fen.account[mid]){
		fen.update(mid);
		return mid;
	}
	int &idx = jump_right[mid];
	while (idx < n){
		query(idx);
		if (type[idx] == type_lollipop){
			break;
		}
		if (not fen.account[idx]){
			fen.update(idx);
			return idx;
		}
		idx++;
	}
	if (idx < n and fen.query(idx + 1, n - 1) != cnt_right[idx]){
		return search_important(idx + 1, r);
	}
	else{
		global_hi = min(global_hi, mid - 1);
		return search_important(l, mid - 1);
	}
	return -1;
}

int find_best(int _n){
	n = _n;
	int min_lollipop = find_min_lollipop();
	int max_important = n - min_lollipop;
	int lim = min(n, max_important + 1);
	for (int i = 0; i < lim; i++){
		query(i);
		if (type[i] == 0){
			return i;
		}
	}
	type_lollipop = *max_element(type, type + lim);
	for (int i = 0; i < lim; i++){
		if (type[i] != type_lollipop){
			fen.update(i);
		}
	}
	iota(jump_right, jump_right + n, 1);
	global_hi = n - 1;
	while (true){
		int idx = search_important(lim, global_hi);
		if (type[idx] == 0){
			return idx;
		}
	}
	return -1;
}

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