Submission #417862

#	Time	Username	Problem	Language	Result	Execution time	Memory
417862		Kevin_Zhang_TW	The short shank; Redemption (BOI21_prison)	C++17	35 / 100	198 ms	460 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 = 4005, inf = 1e9;

int dp[MAX_N], cnt[MAX_N];

int dp2[MAX_N][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);
	for (int i = n;i >= 1;--i) {
		for (int j = i;j < nxt[i];++j)
			ok[j] = true;

		dp[i] = accumulate(begin(ok)+i, end(ok), 0) + cost;

		cnt[i] = 1;

		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));
	}

	//{
	//	auto [c, w] = solve_dp(0);
	//	DE(c, w);
	//	if (c <= D) {
	//		cout << w << '\n';
	//		return 0;
	//	}
	//}

	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:76:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   76 |   mid = l + r >> 1;
      |         ~~^~~

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