Submission #541282

#	Time	Username	Problem	Language	Result	Execution time	Memory
541282		fcw	Global Warming (CEOI18_glo)	C++17	100 / 100	398 ms	14144 KiB

glo

#include <bits/stdc++.h>
#define st first
#define nd second
using lint = int64_t;
constexpr int mod = int(1e9) + 7;
constexpr int inf = 0x3f3f3f3f;
constexpr int ninf = 0xcfcfcfcf;
constexpr lint linf = 0x3f3f3f3f3f3f3f3f;
const long double pi = acosl(-1.0);
// Returns -1 if a < b, 0 if a = b and 1 if a > b.
int cmp_double(double a, double b = 0, double eps = 1e-9) {
	return a + eps > b ? b + eps > a ? 0 : 1 : -1;
}
using namespace std;

template<class I> vector<int> lis(const vector<I>& S) {
	if (S.empty()) return {};
	vector<int> prev(S.size());
	typedef pair<I, int> p;
	vector<p> res;
	for(int i = 0; i < (int)S.size(); i++) {
		// change 0 -> i for longest non-decreasing subsequence
		auto it = lower_bound(res.begin(), res.end(), p {S[i], i});
		if (it == res.end()) res.emplace_back(), it = res.end()-1;
		*it = {S[i], i};
		prev[i] = it == res.begin() ? 0 : (it-1)->second;
	}
	int L = res.size(), cur = res.back().second;
	vector<int> ans(L);
	while (L--) ans[L] = cur, cur = prev[cur];
	return ans;
}

int main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	//ifstream cin;
	//cin.open("cowjog.in");
	//ofstream cout;
	//cout.open("cowjog.out");
	int n, x;
	cin>>n>>x;
	vector<int>a(n);
	for(int i=0;i<n;i++) cin>>a[i];

	auto solve = [&](vector<int>&v)->int{
		map<int, int>dp[2];
		dp[0][-inf] = 0;
		dp[1][-inf] = 0;
		for(int i=0;i<n;i++){
			{
				int cur = v[i] + x;
				auto it = dp[0].lower_bound(cur);
				int val = prev(it)->nd + 1;
				it = dp[1].upper_bound(cur);
				if(prev(it)->nd < val){
					dp[1][cur] = val;
					it = dp[1].lower_bound(cur);
					while(next(it) != dp[1].end() && next(it)->nd <= val) dp[1].erase(next(it));
				}
			}
			for(int j=0;j<2;j++){
				int cur = v[i] + j * x;
				auto it = dp[j].lower_bound(cur);
				if(it == dp[j].end() || it->st != cur){
					int val = prev(it)->nd + 1;
					dp[j][cur] = val;
					it = dp[j].lower_bound(cur);
					while(next(it) != dp[j].end() && next(it)->nd <= val) dp[j].erase(next(it));
				}
			}

		}
		return dp[1].rbegin()->nd;
	};
	vector<int>b = a, c = a;
	reverse(c.begin(), c.end());
	for(int i=0;i<n;i++) c[i] = -c[i];
	cout<<max(solve(b), solve(c))<<"\n";
	return 0;
}
/*
[  ]Leu o problema certo???
[  ]Ver se precisa de long long
[  ]Viu o limite dos fors (é n? é m?)
[  ]Tamanho do vetor, será que é 2e5 em vez de 1e5??
[  ]Testar sample
[  ]Testar casos de  borda
[  ]1LL no 1LL << i
[  ]Testar mod (é 1e9+7, mesmo?, será que o mod não ficou negativo?)
*/

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 17 / 17
• Subtask 7: 25 / 25