Submission #417909

#	Time	Username	Problem	Language	Result	Execution time	Memory
417909		Kevin_Zhang_TW	The short shank; Redemption (BOI21_prison)	C++17	80 / 100	2050 ms	66844 KiB

prison

#include <bits/stdc++.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 = 2e6 + 10, inf = 1e9;

int dp[MAX_N], cnt[MAX_N];

int n, D, T;

//           i can activate [i, nxt[i])
int s[MAX_N], nxt[MAX_N];

pair<int,int> solve_dp(int cost) {

	vector<int> ok(n + 10), cur_nxt(n + 10);

	int diff_sum = 0;

	// index,    a[i] - a[i-1],  cnt[i]
	map<int, pair<int,int>> mono;
	

	auto pops = [&](auto it) {
		while (it != begin(mono) && it != end(mono)) {
			auto pit = prev(it);
			auto [_, cl] = pit->second;
			auto [d, cr] = it->second;

			if (d == 0 && cr >= cl) {
				it = mono.erase(it);
				continue;
			}
			if (d > 0) {
				if (next(it) == end(mono)) {
					diff_sum -= d;
				}
				else {
					next(it)->second.first += d;
				}
				it = mono.erase(it);
			}
			else break;
		}
	};

	// for all value >= index will be add 1
	auto mono_add = [&](int ind) {
		auto it = mono.lower_bound(ind);
		if (it == end(mono)) return;
		++it->second.first;
		++diff_sum;
		pops(it);
	};
	auto mono_push_front = [&](int ind, int dp, int cnt) {
		if (mono.empty()) {
			mono[ind] = {dp, cnt};
			diff_sum = dp;
			return;
		}
		auto &[d, c] = mono.begin()->second;
		d -= dp;
		mono[ind] = {dp, cnt};
		pops(next(begin(mono)));
	};

	int cnt1 = 0;
	for (int i = n;i >= 1;--i) {
		cur_nxt[i] = nxt[i];
		for (int j = i;j < nxt[i];++j) {
			if (ok[j]) {
				assert(cur_nxt[j] > j);
				chmax(cur_nxt[i], cur_nxt[j]);
				j = cur_nxt[j] - 1;
			}
			else {
				ok[j] = true, ++cnt1;

				mono_add(j + 1);
			}
		}

		dp[i] = cnt1 + cost;

		cnt[i] = 1;

		if (mono.size()) {
			auto [_, c] = prev(end(mono))->second;
			if (chmin(dp[i], cost + diff_sum))
				cnt[i] = c + 1;
			if (dp[i] == cost + diff_sum)
				cnt[i] = c + 1;
		}

		mono_push_front(i, dp[i], cnt[i]);

//		int sum = 0;
//		for (int k = i+1;k <= n;++k) { 
//			sum += ok[k-1];
//
//			if (chmin(dp[i], cost + sum + dp[k]))
//				cnt[i] = cnt[k]+1;
//
//			if (dp[i] == cost + sum + dp[k])
//				chmin(cnt[i], cnt[k]+1);
//		}
//
	}

	return make_pair(cnt[1], dp[1]);
}

int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> D >> T; ++D;
	// Just to be faster
	//assert(n < MAX_N);

	for (int i = 1;i <= n;++i) {
		cin >> s[i];
		nxt[i] = min(n+1, max(i, i + T - s[i] + 1));
	}

	int l = 0, r = n, mid;
	while (l < r) {
		mid = l + r >> 1;
		auto [c, w] = solve_dp(mid);
		if (c > D)
			l = mid+1;
		else
			r = mid;
	}

	auto [c, w] = solve_dp(l);

	cout << w - l * D << '\n';
}

Compilation message (stderr)

prison.cpp: In function 'int32_t main()':
prison.cpp:139:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  139 |   mid = l + r >> 1;
      |         ~~^~~

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 0 / 20