Submission #60452

#	Time	Username	Problem	Language	Result	Execution time	Memory
60452		kingpig9	Shortcut (IOI16_shortcut)	C++11	71 / 100	2051 ms	13148 KiB

shortcut

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

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> edge;
const int MAXN = 1 << 17;

#define debug(...) fprintf(stderr, __VA_ARGS__)
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define fillchar(a, s) memset((a), (s), sizeof(a))

template<class T>
void setmin (T &a, T b) {
	if (b < a) {
		a = b;
	}
}

template<class T>
void setmax (T &a, T b) {
	if (a < b) {
		a = b;
	}
}

int N;
ll C;
ll L[MAXN];	//total length
ll D[MAXN];	//distance to secondary station (i + N)

bool moo_slow (ll dia) {
	//is diameter <= dia?
	ll xmymn = LLONG_MIN, xmymx = LLONG_MAX;
	ll xpymn = LLONG_MIN, xpymx = LLONG_MAX;

	for (int i = 0; i < N; i++) {
		for (int j = i + 1; j < N; j++) {
			if ((D[i] - L[i]) + (D[j] + L[j]) > dia) {
				//ll lim = dia - D[i] - D[j] - C;
				//L[i] - L[j] - lim <= x - y <= L[i] - L[j] + lim
				//L[i] + L[j] - lim <= x + y <= L[i] + L[j] + lim
				setmax(xmymn, (L[i] + D[i]) + (-L[j] + D[j]) - dia + C);
				setmin(xmymx, (L[i] - D[i]) + (-L[j] - D[j]) + dia - C);
				setmax(xpymn, (L[i] + D[i]) + (L[j] + D[j]) - dia + C);
				setmin(xpymx, (L[i] - D[i]) + (L[j] - D[j]) + dia - C);
			}
			//otherwise everything works
		}
	}
	//debug("x - y: min = %lld, max = %lld.\nx + y: min = %lld, max = %lld.\n", xmymn, xmymx, xpymn, xpymx);

	if (xmymn > xmymx || xpymn > xpymx) {
		return false;
	}

	debug("xmymn = %lld, xmymx = %lld. xpymn = %lld, xpymx = %lld.\n", xmymn, xmymx, xpymn, xpymx);

	if (xmymn == LLONG_MIN) {
		return true;
	}

	//ok now check if anything is in there
	for (int i = 0; i < N; i++) {
		for (int j = i + 1; j < N; j++) {
			if (xmymn <= L[i] - L[j] && L[i] - L[j] <= xmymx) {
				if (xpymn <= L[i] + L[j] && L[i] + L[j] <= xpymx) {
					return true;
				}
			}
		}
	}
	return false;
}

//max segtree
struct segtree {
	ll tree[2 * MAXN];

	segtree() {
		for (int i = 0; i < 2 * MAXN; i++) {
			tree[i] = LLONG_MIN;
		}
	}

	void update (int x, ll v) {
		for (tree[x += MAXN] = v; x >>= 1; ) {
			tree[x] = max(tree[2 * x], tree[2 * x + 1]);
		}
	}

	ll query (int a, int b, int cur = 1, int lt = 0, int rt = MAXN) {
		if (rt <= a || b <= lt) {
			return LLONG_MIN;
		}

		if (a <= lt && rt <= b) {
			return tree[cur];
		}

		int mid = (lt + rt) / 2;
		return max(query(a, b, 2 * cur, lt, mid), query(a, b, 2 * cur + 1, mid, rt));
	}
};

segtree seglpd = segtree(), segdml = segtree();

bool moo (ll dia) {
	//debug("DIA = %lld\n", dia);
	//return moo_slow(dia);
	ll xmymn = LLONG_MIN, xmymx = LLONG_MAX;
	ll xpymn = LLONG_MIN, xpymx = LLONG_MAX;

	vector<pair<ll, int>> vdml, vdpl;
	for (int i = 0; i < N; i++) {
		vdml.push_back(make_pair(D[i] - L[i], i));
		vdpl.push_back(make_pair(D[i] + L[i], i));
	}
	sort(all(vdml));
	sort(all(vdpl));

	/*
	debug("D:"); for (int i = 0; i < N; i++) debug(" %lld", D[i]); debug("\n");
	debug("L:"); for (int i = 0; i < N; i++) debug(" %lld", L[i]); debug("\n");

	debug("D - L:");
	for (auto p : vdml) {
		debug(" %lld", p.fi);
	}
	debug("\n");
	debug("D + L:");
	for (auto p : vdpl) {
		debug(" %lld", p.fi);
	}
	debug("\n");
	*/

	//reset entire segtree
	for (int i = 0; i < N; i++) {
		seglpd.update(i, LLONG_MIN);
		segdml.update(i, LLONG_MIN);
	}

	//vdml[vi].fi + vdpl[vj].fi > dia
	for (int vj = 0, vi = N; vj < N; vj++) {
		int j = vdpl[vj].se;
		while (vi > 0 && vdml[vi - 1].fi + vdpl[vj].fi > dia) {
			//add it in
			vi--;
			//add vi
			int i = vdml[vi].se;
			seglpd.update(i, L[i] + D[i]);
			segdml.update(i, D[i] - L[i]);
			//debug("i = %d, j = %d. Distance = %lld\n", i, j, vdml[vi].fi + vdpl[vj].fi);
		}


		//setmax(xmymn, (L[i] + D[i]) + (-L[j] + D[j]) - dia + C);
		//setmin(xmymx, (L[i] - D[i]) + (-L[j] - D[j]) + dia - C);
		//setmax(xpymn, (L[i] + D[i]) + (L[j] + D[j]) - dia + C);
		//setmin(xpymx, (L[i] - D[i]) + (L[j] - D[j]) + dia - C);
		ll qulpd = seglpd.query(0, j), qudml = segdml.query(0, j);
		if (qulpd != LLONG_MIN) {
			setmax(xmymn, qulpd + (-L[j] + D[j]) - dia + C);
			setmax(xpymn, qulpd + (L[j] + D[j]) - dia + C);
		}
		if (qudml != LLONG_MIN) {
			setmin(xmymx, -qudml + (-L[j] - D[j]) + dia - C);
			setmin(xpymx, -qudml + (L[j] - D[j]) + dia - C);
		}
	}

	//debug("xmymn = %lld, xmymx = %lld. xpymn = %lld, xpymx = %lld.\n", xmymn, xmymx, xpymn, xpymx);
	//basic checks
	if (xmymn > xmymx || xpymn > xpymx) {
		return false;
	}

	if (xmymn == LLONG_MIN) {
		return true;
	}

	for (int j = 1; j < N; j++) {
		ll xmn = max(xpymn - L[j], xmymn + L[j]);
		ll xmx = min(xpymx - L[j], xmymx + L[j]);
		if (xmn > xmx) {
			continue;
		}
		if (upper_bound(L, L + j, xmx) != lower_bound(L, L + j, xmn)) {
			return true;
		}
	}
	return false;
}

ll find_shortcut (int nnn, vector<int> lll, vector<int> ddd, int ccc) {
	//very very preliminary stuff - should also init other stuff
	N = nnn;
	C = ccc;
	L[0] = 0;
	for (int i = 1; i < N; i++) {
		L[i] = L[i - 1] + lll[i - 1];
	}
	for (int i = 0; i < N; i++) {
		D[i] = ddd[i];
	}

	ll lo = 0, hi = (N + 1) * 1000000000ll;
	while (hi - lo > 1) {
		ll mid = (lo + hi) >> 1;
		if (moo(mid)) {
			hi = mid;
		} else {
			lo = mid;
		}
	}
	return hi;
}

• 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