Submission #161208

#	Time	Username	Problem	Language	Result	Execution time	Memory
161208		rama_pang	Global Warming (CEOI18_glo)	C++14	62 / 100	68 ms	5924 KiB

glo

#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;

int N, X;
int A[200005];
int lis[200005];
int lds[200005];
pair<int, int> anslis[200005];
pair<int, int> anslds[200005];


int LIS() {
    for (int i = 0; i <= N; i++) lis[i] = INF, lds[i] = -INF;
    lis[0] = -INF, lds[N] = INF;

    int res = 0;

    for (int i = 0, cur = 0; i < N; i++) {
        int j = upper_bound(lis, lis + N + 1, A[i] - X) - lis;
        if (lis[j - 1] < A[i] - X && A[i] - X < lis[j]) lis[j] = A[i] - X, cur = max(cur, j);
        anslis[i] = {cur, lis[cur]};
    }

    for (int i = N - 1, cur = N - 1; i >= 0; i--) {
        int j = lower_bound(lds, lds + N + 1, A[i]) - lds;
        if (j >= 1 && lds[j - 1] < A[i] && A[i] < lds[j]) lds[j - 1] = A[i], cur = min(cur, j - 1);
        if (j >= 2 && lds[j - 2] < A[i] && A[i] < lds[j - 1]) lds[j - 2] = A[i], cur = min(cur, j - 2);
        
        anslds[i] = {cur, lds[cur]};
    }

    for (int i = 0; i <= N; i++) {
        if (lis[i] < INF) res = max(res, i);
    }

    for (int i = 0; i + 1 < N; i++) {
        if (anslis[i].second < anslds[i + 1].second) 
            res = max(res, anslis[i].first + N - anslds[i + 1].first);
    }

    return res;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> N >> X;
    for (int i = 0; i < N; i++) cin >> A[i];

    int ans = LIS();
    cout << ans << "\n"; 

}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 0 / 13
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 17 / 17
• Subtask 7: 0 / 25