Submission #417919

#	Time	Username	Problem	Language	Result	Execution time	Memory
417919		Kevin_Zhang_TW	The short shank; Redemption (BOI21_prison)	C++17	80 / 100	2078 ms	94492 KiB

prison

#pragma GCC optimize("Ofast")
#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];


struct dsu {
	vector<int> g, sz;
	dsu(int n) {
		g = sz = vector<int>(n + 10);
		iota(AI(g), 0);
		fill(AI(sz), 1);
	}
	int F(int i) { return i == g[i] ? i : g[i] = F(g[i]); }
	void M(int a, int b) {
		a = F(a), b = F(b);
		if (a == b) return;
		if (sz[a] < sz[b]) swap(a, b);
		sz[a] += sz[b], g[b] = a;
	}
	int operator ()(int i) { return F(i); }
};

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

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

	vector<int> ld(n + 10), rd(n + 10), dif(n + 10), cc(n + 10);

	dsu D(n);

	iota(AI(ld), 0), iota(AI(rd), 0);

	int diff_sum = 0, E = n, F = n + 1;

	// index,    a[i] - a[i-1],  cnt[i]
	
	auto mg = [&](int ind, int nxt) {
		dif[ind] = dif[nxt];
		cc[ind] = cc[nxt];
		ld[nxt] = ld[ind];
		rd[ind] = rd[nxt];
		D.M(ind, nxt);
	};
	auto pops = [&](int ind) {
		if (D(ind) == D(F)) return;
		while (ind <= E) {
			ind = D(ind);
			int lst = D( ld[ind]-1 ), nxt = D( rd[ind]+1 );
			int cl = cc[ lst ];
			int d = dif[ ind ], cr = cc[ ind ];
			if (d > 0 || (d == 0 && cr >= cl)) {
				if (ind == D(E)) {
					diff_sum -= d;
					E = ld[ind]-1;
					break;
				}
				else {
					dif[nxt] += dif[ind];
					mg(ind, nxt); //
				}
			}
			else break;
		}
	};

	// for all value >= index will be add 1
	auto mono_add = [&](int ind) {
		if (ind > E) return;
		++diff_sum;
		++dif[ D(ind) ];
		pops(ind);
	};
	auto mono_push_front = [&](int ind, int dp, int cnt) {
		F = ind;
		dif[ind] = dp;
		cc[ind] = cnt;
		if (ind == n) {
			diff_sum = dp;
			return;
		}
		int b = D(ind+1);
		dif[b] -= dp;
		pops(ind+1);
	};
	auto mono_get = [&]() {
		return cc[D(E)];
	};

	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]) {
				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 (i != n) {
			int c = mono_get();
			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]);
	}
	return make_pair(cnt[1], dp[1]);
}

int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> D >> T; ++D;

	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 'std::pair<int, int> solve_dp(int)':
prison.cpp:15:17: warning: statement has no effect [-Wunused-value]
   15 | #define DE(...) 0
      |                 ^
prison.cpp:48:2: note: in expansion of macro 'DE'
   48 |  DE(cost);
      |  ^~
prison.cpp: In function 'int32_t main()':
prison.cpp:154:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  154 |   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