Submission #25749

#	Time	Username	Problem	Language	Result	Execution time	Memory
25749		Hiasat	Shortcut (IOI16_shortcut)	C++14	38 / 100	2000 ms	72588 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 3000;
const ll INF = 1e18;
ll L[N], R[N], mxL[N], mxR[N], pre[N];
vector<int> d, l;
ll dp[N][N];
int n;

ll c;

bool check(ll mid) {
	for (int len = 1; len <= n ; ++len) {
		for (int i = n - len ; i >= 0 ; --i) {
			int j = i + len - 1;
			if (len == 1) {
				dp[i][j] = INF;
				continue;
			}
			if (pre[j] - pre[i] + d[i] + d[j] > mid)
				dp[i][j] = (pre[j] - pre[i]) - d[i] - d[j];
			else
				dp[i][j] = INF;
			dp[i][j] = min(dp[i][j], min(dp[i + 1][j], dp[i][j - 1]));
		}
	}
	for (int i = 0 ; i < n ; i++) {
		if (mxL[i] > mid)
			continue;
		ll fage3 = -INF;
		ll mixer = 0;
		for (int j = i + 1 ; j < n ; j++) {
			fage3 += l[j - 1];
			if (L[j-1] + l[j-1] + d[j] > mid)
				fage3 = max(fage3, L[i] + c + d[j]);
			if (fage3 > mid)
				break;

			if (d[j] + l[j] + R[j + 1] > mid) {
				mixer = max(mixer, pre[j] - pre[i] + d[j] + c);
			}
			if (mxR[j] <= mid) {
				if (L[i] + min(pre[j] - pre[i], c) + R[j] <= mid) {
					if (dp[i][j] == INF || (pre[j] - pre[i] + c) - dp[i][j] <= mid) {
						if (mixer + R[j] <= mid) {
							//cout << i << " " << j << endl;
							return 1;
						}
					}
				}
			}
		}
	}

	return false;
}
ll find_shortcut(int n, vector<int> l, vector<int> d, int c) {
	if (n > 3000)
		return -1;
	::n = n;
	::d = d;
	::c = c;
	::l = l;
	for (int i = 0; i < n; ++i) {
		L[i] = d[i];
		if (i)
			pre[i] = l[i - 1] + pre[i - 1];
		if (i)
			L[i] = max(L[i - 1] + l[i - 1], L[i]);
		mxL[i] = max(i ? mxL[i - 1] : 0, d[i] + (i ? L[i - 1] + l[i - 1] : 0));
	}
	for (int i = n - 1 ; i >= 0 ; i--) {
		R[i] = d[i];
		if (i != n - 1)
			R[i] = max(R[i], R[i + 1] + l[i]);
		mxR[i] = max(i != n - 1 ? mxR[i + 1] : 0, d[i] + (i != n - 1 ? R[i + 1] + l[i] : 0));
	}

	ll lo = *max_element(d.begin(), d.end()) , hi = 1e9 * (N + 3), best = -1;
	while (lo <= hi) {
		ll mid = (lo + hi) / 2;
		if (check(mid)) {
			best = mid;
			hi = mid - 1;
		} else {
			lo = mid + 1;
		}
	}
	assert(best != -1);
	return best;
}

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