Submission #838065

#	Time	Username	Problem	Language	Result	Execution time	Memory
838065		pavement	Shortcut (IOI16_shortcut)	C++17	71 / 100	2077 ms	35780 KiB

shortcut

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

#define mp make_pair
#define pb push_back
#define eb emplace_back

using ll = long long;

ll find_shortcut(int n, vector<int> l, vector<int> d, int c) {
	vector<ll> x(n, 0);
	for (int i = 0; i + 1 < n; i++) {
		x[i + 1] = x[i] + (ll)l[i];
	}
	
	auto good = [&](ll k) {
		ll min_x = -(ll)1e18, max_x = (ll)1e18, min_y = -(ll)1e18, max_y = (ll)1e18;
		{
			vector<tuple<ll, bool, ll, ll*, int> > case_1_events;
			
			for (int i = 0; i < n; i++) {
				case_1_events.eb(d[i] - x[i], 0, x[i] + d[i], nullptr, i);
				case_1_events.eb(k - d[i] - x[i], 1, -k + c + d[i] - x[i], &min_x, i);
				case_1_events.eb(k - d[i] - x[i], 1, -k + c + d[i] + x[i], &min_y, i);
			}
			
			sort(case_1_events.begin(), case_1_events.end(), [](const tuple<ll, bool, ll, ll*, int> &lhs, const tuple<ll, bool, ll, ll*, int> &rhs) {
				auto lp = mp(get<0>(lhs), get<1>(lhs)), rp = mp(get<0>(rhs), get<1>(rhs));
				return lp > rp;
			});
			
			pair<ll, int> case_1_first_best = mp(-(ll)1e18, -1), case_1_second_best = mp(-(ll)1e18, -1);
			
			for (auto [_, type, offset, addr, idx] : case_1_events) {
				if (type == 0) {
					case_1_second_best = max(case_1_second_best, mp(offset, idx));
					if (case_1_second_best > case_1_first_best) {
						swap(case_1_first_best, case_1_second_best);
					}
				} else {
					*addr = max(*addr, (case_1_first_best.second == idx ? case_1_second_best.first : case_1_first_best.first) + offset);
				}
			}
		}
		
		{
			vector<tuple<ll, bool, ll, ll*, int> > case_2_events;
			
			for (int i = 0; i < n; i++) {
				case_2_events.eb(d[i] - x[i], 0, -(x[i] - d[i]), nullptr, i);
				case_2_events.eb(k - d[i] - x[i], 1, k - c - d[i] - x[i], &max_x, i);
				case_2_events.eb(k - d[i] - x[i], 1, k - c - d[i] + x[i], &max_y, i);
			}
			
			sort(case_2_events.begin(), case_2_events.end(), [](const tuple<ll, bool, ll, ll*, int> &lhs, const tuple<ll, bool, ll, ll*, int> &rhs) {
				auto lp = mp(get<0>(lhs), get<1>(lhs)), rp = mp(get<0>(rhs), get<1>(rhs));
				return lp > rp;
			});
			
			pair<ll, int> case_2_first_best = mp(-(ll)1e18, -1), case_2_second_best = mp(-(ll)1e18, -1);
			
			for (auto [_, type, offset, addr, idx] : case_2_events) {
				if (type == 0) {
					case_2_second_best = max(case_2_second_best, mp(offset, idx));
					if (case_2_second_best > case_2_first_best) {
						swap(case_2_first_best, case_2_second_best);
					}
				} else {
					*addr = min(*addr, -(case_2_first_best.second == idx ? case_2_second_best.first : case_2_first_best.first) + offset);
				}
			}
		}
		
		if (min_x <= max_x && min_y <= max_y) {
			set<ll> pos;
			for (int j = 1; j < n; j++) {
				pos.insert(x[j - 1]);
				ll lb = max(min_x + x[j], min_y - x[j]), rb = min(max_x + x[j], max_y - x[j]);
				auto it = pos.lower_bound(lb);
				if (it != pos.end() && *it <= rb) {
					return true;
				}
			}
			return false;
		} else {
			return false;
		}
	};
	
	ll lo = 0, hi = (ll)1e16, ans = -1;
	while (lo <= hi) {
		ll mid = (lo + hi) / 2;
		if (good(mid)) {
			ans = mid;
			hi = mid - 1;
		} else {
			lo = mid + 1;
		}
	}
	
	return ans;
}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 33 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3