Submission #982579

#	Time	Username	Problem	Language	Result	Execution time	Memory
982579		Ghetto	Sequence (APIO23_sequence)	C++17	7 / 100	87 ms	33580 KiB

sequence

#include "sequence.h"
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int MAX_N = 5e5 + 5;

int n;
int a[MAX_N];

vector<pii> ranges[MAX_N];
void precomp() {
    int i = 1;
    while (i != n + 1) {
        int j = i;
        while (j < n && a[j + 1] == a[i]) j++;
        ranges[a[i]].push_back({i, j});
        i = j + 1;
    }
}

int sequence(int tmp_n, vector<int> tmp_a) {
    n = tmp_n;
    for (int i = 0; i < n; i++) a[i + 1] = tmp_a[i];

    precomp();

    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (ranges[i].empty()) continue;
        for (pii x : ranges[i]) ans = max(ans, x.second - x.first + 1);
        if (ranges[i].size() == 1) continue;

        assert(ranges[i].size() == 2);
        int range_size = 0;
        for (pii x : ranges[i]) range_size += x.second - x.first + 1;
        int in_size = ranges[i][1].first - ranges[i][0].second + 1;
        int out_size = ranges[i][0].first - 1 + n - ranges[i][1].second;
        if (out_size >= in_size - range_size) ans = max(ans, range_size);
    }
    return ans;
} 

• Subtask 1: 0 / 11
• Subtask 2: 0 / 17
• Subtask 3: 7 / 7
• Subtask 4: 0 / 12
• Subtask 5: 0 / 13
• Subtask 6: 0 / 22
• Subtask 7: 0 / 18