Submission #753964

#	Time	Username	Problem	Language	Result	Execution time	Memory
753964		nguyentunglam	Sequence (APIO23_sequence)	C++17	0 / 100	2075 ms	41380 KiB

sequence

#include<bits/stdc++.h>
#define fi first
#define se second
#define endl "\n"
#define ii pair<int, int>
using namespace std;
const int N = 5e5 + 10;
int cnt[N], lmin[N], lmax[N], rmin[N], rmax[N], sum[N];
vector<int> pos[N];
bool check(int lx, int rx, int ly, int ry) {
    return !(rx < ly || ry < lx);
}
int sequence(int n, vector<int> a) {
    for(int i = 0; i < n; i++) pos[a[i]].push_back(i);
    int res = 0;
    for(int val = 1; val <= n; val++) {
        sum[0] = 0;
        for(int i = 0; i < n; i++) {
            if (i > 0) {
                lmin[i] = lmin[i - 1];
                lmax[i] = lmax[i - 1];
            }
            if (i > 0) sum[i] = sum[i - 1];
            if (a[i] <= val) sum[i]--;
            else sum[i]++;
            lmin[i] = min(lmin[i], sum[i]);
            lmax[i] = max(lmax[i], sum[i]);
        }
        rmin[n] = 1e9; rmax[n] = 0;
        for(int i = n - 1; i >= 0; i--) {
            rmin[i] = min(rmin[i + 1], sum[i]);
            rmax[i] = max(rmax[i + 1], sum[i]);
        }
//        for(int i = 0; i < n; i++) cout << sum[i] << " "; cout << endl;
//        cout << lmin[0] << " " << lmax[0] << endl;
//        cout << rmin[n - 1] << " " << rmax[n - 1] << endl;
        int j = 0;
        for(int i = 0; i < pos[val].size(); i++) {
            while (!check(lmin[pos[val][j]] - 1, lmax[pos[val][j]], rmin[pos[val][i]], rmax[pos[val][i]])) j++;
            res = max(res, i - j + 1);
//            if (val == 1 && i == 1) {
//                for(int i = 0; i < n; i++) cout << sum[i] << " "; cout << endl;
//                cout << lmin[pos[val][j]] << " " << lmax[pos[val][j]] << endl;
//                cout << rmin[pos[val][i]] << " " << rmax[pos[val][i]] << endl;
//            }
        }
    }
//    cout << endl;
    return res;
}

#ifdef ngu
int main() {

    freopen ("task.inp", "r", stdin);
    freopen ("task.out", "w", stdout);

//    int n; cin >> n;
//    vector<int> a(n);
//    for(int i = 0; i < n; i++) cin >> a[i];
//    cout << sequence(n, a);
//    cout << sequence(7, {1, 2, 3, 1, 2, 1, 3}) << endl;
//    cout << sequence(9, {1, 1, 2, 3, 4, 3, 2, 1, 1}) << endl;
//    cout << sequence(14, {2, 6, 2, 5, 3, 4, 2, 1, 4, 3, 5, 6, 3, 2}) << endl;

}
#endif // ngu

Compilation message (stderr)

sequence.cpp: In function 'int sequence(int, std::vector<int>)':
sequence.cpp:38:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |         for(int i = 0; i < pos[val].size(); i++) {
      |                        ~~^~~~~~~~~~~~~~~~~

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