Submission #421557

#	Time	Username	Problem	Language	Result	Execution time	Memory
421557		Kevin_Zhang_TW	Shortcut (IOI16_shortcut)	C++17	0 / 100	1 ms	292 KiB

shortcut

#include <bits/stdc++.h>
#include "shortcut.h"
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif

const int MAX_N = 3010;
// inf is big enough
const ll inf = 1ll << 59;

int n, C;
ll pf[MAX_N], suf[MAX_N], loc[MAX_N];
ll pfd[MAX_N], sufd[MAX_N];

ll dis(int i, int j) {
	return abs(loc[i] - loc[j]);
}

vector<int> l, d;

void init() {
	for (int i = 0;i+1 < n;++i) {
		loc[i+1] = loc[i] + l[i];
	}

	{
		pfd[0] = pf[0] = d[0];
		for (int i = 1;i < n;++i) {
			pf[i] = max(pf[i-1], d[i] - loc[i]);
			pfd[i] = max(pfd[i-1], d[i] + loc[i] + pf[i-1]);
		}
	}
	{
		sufd[n-1] = suf[n-1] = d[n-1];
		for (int i = n-2;i >= 0;--i) {
			suf[i] = max(suf[i+1], d[i] - (loc[n-1] - loc[i]));
			sufd[i] = max(sufd[i+1], d[i] + (loc[n-1] - loc[i]) + suf[i+1]);
		}
	}

}
ll cal(int a, int b) {
	//if (C >= dis(a, b)) return inf - b;
	ll C = min((ll)::C, dis(a, b));

	ll ld = dis(0, a) + pf[a], rd = dis(b, n-1) + suf[b];

	ll res = max({pfd[a], sufd[b], 
			ld + rd + C});

	for (int i = a;i <= b;++i) {
		// first to l, r
		ll tol = min(dis(i, a), dis(i, b) + C),
		   tor = min(dis(i, b), dis(i, a) + C);

		if (i > a) chmax(res, d[i] + tol + ld);
		if (i < b) chmax(res, d[i] + tor + rd);

		for (int j = i+1;j <= b;++j) {
			ll dij = min(dis(i, j), C + dis(a, b) - dis(i, j));
			chmax(res, d[i] + d[j] + dij);
		}
	}
//
//	auto nxt = [&](int i) {
//		return i < b ? i+1 : a;
//	};
//	auto gdis = [&](int i, int j) {
//		return min(dis(i, j), dis(a, b) + C - dis(i, j));
//	};
//	// tor distance
//	auto rdis = [&](int i, int j) {
//		if (j < i) return dis(a, b) + C - dis(i, j);
//		return dis(i, j);
//	};
//	for (int i = a, j = a;i <= b;++i) {
//		deque<pair<ll,ll>> dq;
//		while (nxt(j) != i && gdis(i, nxt(j)) == rdis(i, nxt(j))) {
//			j = nxt(j);
//			push_in(j); 
//		}
//		while (dq.size() && dq[0].first <= i)
//
//	}
//
	DE(a, b, res);
	return res;
}

long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c) {
	::n = n;
	::l = l;
	::d = d;
	C = c;

	init();

	ll res = pfd[n-1];

	function<void(int,int,int,int)> dcop = [&](int l, int r, int sl, int sr) {
		if (l > r) return;
		int mid = l + r >> 1;
		int bst = -1;
		ll ans = inf;
		for (int i = sl;i <= sr && i < mid;++i) {
			if (chmin(ans, cal(i, mid)))
				bst = i;
		}
		chmin(res, ans);

		dcop(l, mid-1, sl, bst);
		dcop(mid+1, r, bst, sr);

	};

	dcop(0, n-1, 0, n-1);

//	for (int i = 0;i < n;++i) {
//		int l = i+1, r = n-1, mid;
//		while (l < r) {
//			mid = l + r >> 1;
//			if (cal(i, mid) > cal(i, mid+1))
//				l = mid+1;
//			else
//				r = mid;
//		}
//		chmin(res, cal(i, l));
////		for (int j = i+1;j < n;++j)
////			chmin(res, cal(i, j));
//	}

	return res;
}

Compilation message (stderr)

shortcut.cpp: In function 'll cal(int, int)':
shortcut.cpp:15:17: warning: statement has no effect [-Wunused-value]
   15 | #define DE(...) 0
      |                 ^
shortcut.cpp:98:2: note: in expansion of macro 'DE'
   98 |  DE(a, b, res);
      |  ^~
shortcut.cpp: In lambda function:
shortcut.cpp:114:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  114 |   int mid = l + r >> 1;
      |             ~~^~~

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