Submission #96932

#	Time	Username	Problem	Language	Result	Execution time	Memory
96932		youngyojun	Shortcut (IOI16_shortcut)	C++11	97 / 100	2073 ms	61192 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
#define INFLL (0x3f3f3f3f3f3f3f3fll)
using namespace std;
typedef long long ll;
inline void upmin(ll &a, ll b) { if(b < a) a = b; }
inline void upmax(ll &a, ll b) { if(a < b) a = b; }

const int MAXN = 1000055;

ll X[MAXN], L[MAXN];
int O[MAXN], OJ[MAXN];

int N; ll K, Ans;

bool isp(ll Y) {
	ll xymx = -INFLL, xymn = INFLL, yxmx = -INFLL, yxmn = INFLL;
	ll mx[2] = {-INFLL, -INFLL}, mn[2] = {INFLL, INFLL};
	int mxi[2] = {-1, -1}, mni[2] = {-1, -1};
	for(int oi = 0, i, oj = 0, j; oj < N; oj++) {
		j = OJ[oj];
		for(ll t = Y-X[j]-L[j], c; oi < N; oi++) {
			i = O[oi];
			if(L[i]-X[i] <= t) break;
			c = X[i]+L[i];
			if(mx[0] < c) { swap(mx[0], c); swap(mxi[0], i); }
			if(mx[1] < c) { swap(mx[1], c); swap(mxi[1], i); }
			i = O[oi]; c = X[i]-L[i];
			if(c < mn[0]) { swap(mn[0], c); swap(mni[0], i); }
			if(c < mn[1]) { swap(mn[1], c); swap(mni[1], i); }
		}
		ll rmx = j == mxi[0] ? mx[1] : mx[0];
		ll rmn = j == mni[0] ? mn[1] : mn[0];
		upmin(xymn, Y-K + rmn + X[j]-L[j]);
		upmax(xymx, K-Y + rmx + X[j]+L[j]);
		upmin(yxmn, Y-K - rmx + X[j]-L[j]);
		upmax(yxmx, K-Y - rmn + X[j]+L[j]);
	}
	for(int s = 0, xymxi = N-1, xymni = N-1, yxmxi = 0, yxmni = 0; s < N; s++) {
		for(ll t = xymx-X[s]; xymxi && t <= X[xymxi-1]; xymxi--);
		for(ll t = xymn-X[s]; 0 <= xymni && t < X[xymni]; xymni--);
		for(ll t = yxmx+X[s]; yxmxi < N && X[yxmxi] < t; yxmxi++);
		for(ll t = yxmn+X[s]; yxmni+1 < N && X[yxmni+1] <= t; yxmni++);
		if(X[xymxi] < xymx-X[s] || yxmn+X[s] < X[yxmni]) continue;
		if(max(xymxi, yxmxi) <= min(xymni, yxmni)) return true;
	}
	return false;
}

ll getAns() {
	ll mx = -INFLL;
	for(int i = 0; i < N; i++) {
		upmax(Ans, X[i]+L[i] + mx);
		upmax(mx, L[i]-X[i]);
	}
	iota(O, O+N, 0); sort(O, O+N, [&](int a, int b) {
		return L[a]-X[a] > L[b]-X[b];
	});
	iota(OJ, OJ+N, 0); sort(OJ, OJ+N, [&](int a, int b) {
		return X[a]+L[a] < X[b]+L[b];
	});
	ll a = 0, b = 0;
	for(int i = 0; i < N; i++) {
		ll c = L[i];
		if(a < c) swap(a, c);
		if(b < c) swap(b, c);
	}
	ll s = a+b, e = Ans;
	for(ll m; s < e;) {
		m = (s+e) >> 1;
		if(isp(m)) e = m;
		else s = m+1;
	}
	return min(Ans, s);
}

long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c) {
	::N = n; ::K = c;
	for(int i = 1; i < N; i++) ::X[i] = ::X[i-1] + l[i-1];
	for(int i = 0; i < N; i++) ::L[i] = d[i];
    return getAns();
}

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