Submission #922606

#	Time	Username	Problem	Language	Result	Execution time	Memory
922606		maxFedorchuk	Cat (info1cup19_cat)	C++17	25 / 100	320 ms	31840 KiB

cat

#include "bits/stdc++.h"
using namespace std;

const long long MX=2e5+10;

int a[MX];
int p[MX];

pair < int , int > vp1[MX];
pair < int , int > vp2[MX];

int n;

void swp(int i,int j) {
    swap(a[i], a[j]);
    swap(p[a[i]], p[a[j]]);

    swap(a[n - i + 1], a[n - j + 1]);
    swap(p[a[n - i + 1]], p[a[n - j + 1]]);
}

void fun() {
    cin >> n;

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        p[a[i]] = i;
    }

    for (int i = 1; i <= n / 2; i++) {
        if (a[i] + a[n - i + 1] != (n + 1)) {
            cout << "-1\n";
            return;
        }
    }

    int o1 = 0, o2 = 0;
    for (int i = 1; i <= n / 2; i++) {
        if (a[i] == i) {
            continue;
        }

        if (a[i] == a[n - i + 1]) {
            vp1[++o1] = make_pair(i, n - i + 1);
        } else {
            vp2[++o2] = make_pair(i, p[i]);
            swp(i, p[i]);
        }
    }

    if (o1 & 1) {
        cout << "-1\n";
        return;
    }

    while (o1) {
        vp2[++o2] = make_pair(vp1[o1].first, vp1[o1 - 1].first);
        vp2[++o2] = make_pair(vp1[o1].first, vp1[o1 - 1].second);
        o1 -= 2;
    }

    cout << o2 << " " << o2 << "\n";

    for (int i = 1; i <= o2; i++) {
        cout << vp2[i].first << " " << vp2[i].second << "\n";
    }
}
int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(0);

    int t;
    cin >> t;

    while (t--) {
        fun();
    }
}

• Subtask 1: 0 / 15
• Subtask 2: 10 / 10
• Subtask 3: 0 / 25
• Subtask 4: 15 / 15
• Subtask 5: 0 / 35