Submission #398486

# Submission time Handle Problem Language Result Execution time Memory
398486 2021-05-04T11:37:05 Z MarcoMeijer Cat (info1cup19_cat) C++14
18 / 100
567 ms 29848 KB
#include <bits/stdc++.h>
using namespace std;
 
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e18
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
 
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
 
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const vector<T>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class T> void OUT(const vector<T>& x) {RE(i,x.size()) OUT(i==0?"":" ",x[i]);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
 
// dp
template<class T> bool ckmin(T&a, T&b) { bool bl = a > b; a = min(a,b); return bl;}
template<class T> bool ckmax(T&a, T&b) { bool bl = a < b; a = max(a,b); return bl;}
 
void program();
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    program();
}
 
 
//===================//
//   begin program   //
//===================//
 
const int MX = 5e5;
const int N = (1<<20);

int testCases;
int n, a[MX], ra[MX];

void program() {
    IN(testCases);
    while(testCases--) {
        IN(n);
        RE1(i,n) IN(a[i]);
        RE1(i,n) ra[a[i]] = i;

        bool possible = true;
        RE1(i,n) if(a[i] + a[n-i+1] != n+1) possible = false;

        vi wrongSide;
        RE1(i,n/2) if(a[i] > n/2) wrongSide.pb(a[i]);

        if(wrongSide.size()%2) possible = false;

        if(!possible) {
            OUTL(-1);
            continue;
        }

        vii ans;
        auto makeSwap = [&](int x, int y) {
            swap(a[x],a[y]);
            swap(a[n-x+1], a[n-y+1]);
            ra[a[x]] = x;
            ra[a[n-x+1]] = n-x+1;
            ra[a[y]] = y;
            ra[a[n-y+1]] = n-y+1;
            ans.pb({x,y});
        };

        RE(i,wrongSide.size()) {
            makeSwap(ra[wrongSide[i]], ra[n-wrongSide[i+1]+1]);
            i++;
        }

        RE1(i,n) if(a[i] != i) {
            makeSwap(i,a[i]);
        }

        OUTLS(ans.size(),ans.size());
        FOR(p,ans) OUTL(p);
    }
}
# Verdict Execution time Memory Grader output
1 Partially correct 5 ms 332 KB Valid reconstruction
# Verdict Execution time Memory Grader output
1 Correct 24 ms 1152 KB Correctly distinguished between possibility and impossibility
2 Correct 22 ms 916 KB Correctly distinguished between possibility and impossibility
# Verdict Execution time Memory Grader output
1 Partially correct 5 ms 332 KB Valid reconstruction
2 Correct 24 ms 1152 KB Correctly distinguished between possibility and impossibility
3 Correct 22 ms 916 KB Correctly distinguished between possibility and impossibility
4 Correct 28 ms 1220 KB Correctly distinguished between possibility and impossibility
5 Correct 10 ms 588 KB Correctly distinguished between possibility and impossibility
6 Correct 9 ms 596 KB Correctly distinguished between possibility and impossibility
# Verdict Execution time Memory Grader output
1 Correct 24 ms 1152 KB Correctly distinguished between possibility and impossibility
2 Correct 22 ms 916 KB Correctly distinguished between possibility and impossibility
3 Correct 489 ms 26444 KB Correctly distinguished between possibility and impossibility
4 Correct 463 ms 25528 KB Correctly distinguished between possibility and impossibility
5 Correct 490 ms 28304 KB Correctly distinguished between possibility and impossibility
# Verdict Execution time Memory Grader output
1 Partially correct 5 ms 332 KB Valid reconstruction
2 Correct 24 ms 1152 KB Correctly distinguished between possibility and impossibility
3 Correct 22 ms 916 KB Correctly distinguished between possibility and impossibility
4 Correct 28 ms 1220 KB Correctly distinguished between possibility and impossibility
5 Correct 10 ms 588 KB Correctly distinguished between possibility and impossibility
6 Correct 9 ms 596 KB Correctly distinguished between possibility and impossibility
7 Correct 489 ms 26444 KB Correctly distinguished between possibility and impossibility
8 Correct 463 ms 25528 KB Correctly distinguished between possibility and impossibility
9 Correct 490 ms 28304 KB Correctly distinguished between possibility and impossibility
10 Correct 547 ms 26416 KB Correctly distinguished between possibility and impossibility
11 Correct 494 ms 24480 KB Correctly distinguished between possibility and impossibility
12 Correct 507 ms 28392 KB Correctly distinguished between possibility and impossibility
13 Correct 567 ms 29848 KB Correctly distinguished between possibility and impossibility
14 Correct 518 ms 27976 KB Correctly distinguished between possibility and impossibility