oj.uz

Submission #468825

# Submission time Handle Problem Language Result Execution time Memory
468825 2021-08-29T18:52:54 Z errorgorn Cat (info1cup19_cat) C++17
100 / 100
 585 ms 29388 KB 
//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl

#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

const int MOD=998244353;

ll qexp(ll b,ll p,int m){
    ll res=1;
    while (p){
        if (p&1) res=(res*b)%m;
        b=(b*b)%m;
        p>>=1;
    }
    return res;
}

ll inv(ll i){
	return qexp(i,MOD-2,MOD);
}

ll fix(ll i){
	i%=MOD;
	if (i<0) i+=MOD;
	return i;
}

ll fac[1000005];
ll ifac[1000005];

ll nCk(int i,int j){
	if (i<j) return 0;
	return fac[i]*ifac[j]%MOD*ifac[i-j]%MOD;
}

int n;
int arr[200005];
int par[200005];
bool vis[200005];
int brr[200005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	fac[0]=1;
	rep(x,1,1000005) fac[x]=fac[x-1]*x%MOD;
	ifac[1000004]=inv(fac[1000004]);
	rep(x,1000005,1) ifac[x-1]=ifac[x]*x%MOD;
	
	int TC;
	cin>>TC;
	while (TC--){
		cin>>n;
		rep(x,0,n) cin>>arr[x];
		rep(x,0,n) par[x]=0;
		rep(x,0,n) brr[x]=arr[x];
		
		bool can=true;
		rep(x,0,n) if (arr[x]+arr[n-1-x]!=n+1) can=false;
		
		if (!can){
			cout<<"-1"<<endl;
			continue;
		}
		
		n/=2;
		rep(x,0,n) if (arr[x]>n) arr[x]=2*n+1-arr[x],par[x]=1;
		
		rep(x,0,n) arr[x]--;
		//rep(x,0,n) cout<<arr[x]<<" "; cout<<endl;
		//rep(x,0,n) cout<<par[x]<<" "; cout<<endl;
		
		vector<int> bad;
		rep(x,0,n) vis[x]=false;
		rep(x,0,n) if (!vis[x]){
			int curr=x;
			int npar=0;
			int pos=-1;
			
			do{
				vis[curr]=true;
				if (par[curr]) npar^=1,pos=curr;
				curr=arr[curr];
			} while (curr!=x);
			
			if (npar) bad.pub(pos);
		}
		
		if (sz(bad)%2==1){
			cout<<"-1"<<endl;
			continue;
		}
		
		//for (auto &it:bad) cout<<it<<" "; cout<<endl;
	
		vector<ii> v;
		rep(x,0,sz(bad)/2){
			v.pub(ii(bad[x*2]+1,2*n-bad[x*2+1]));
			swap(arr[bad[x*2]],arr[bad[x*2+1]]);
			par[bad[x*2]]=0,par[bad[x*2+1]]=0;
		}
		
		//rep(x,0,n) cout<<arr[x]<<" "; cout<<endl;
		//rep(x,0,n) cout<<par[x]<<" "; cout<<endl;
		
		rep(x,0,n) vis[x]=false;
		rep(x,0,n) if (!vis[x]){
			int curr=x;
			
			do{
				vis[curr]=true;
				if (x!=curr){
					if (par[x]){
						v.pub(ii(x+1,2*n-curr));
						par[x]=par[curr]^1;
					}
					else{
						v.pub(ii(x+1,curr+1));
						par[x]=par[curr];
					}
				}
				curr=arr[curr];
			} while (curr!=x);
		}
		
		cout<<sz(v)<<" "<<sz(v)<<endl;
		for (auto &it:v) cout<<it.fi<<" "<<it.se<<endl;
		
		for (auto &it:v){
			swap(brr[it.fi-1],brr[it.se-1]);
			swap(brr[n*2-it.fi],brr[n*2-it.se]);
		}
		//rep(x,0,n*2) cout<<brr[x]<<" "; cout<<endl;
	}
}

Subtask #1
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 15952 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 41 ms 16092 KB Output is correct
2 Correct 40 ms 16132 KB Output is correct

Subtask #3
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 15952 KB Output is correct
2 Correct 41 ms 16092 KB Output is correct
3 Correct 40 ms 16132 KB Output is correct
4 Correct 44 ms 16516 KB Output is correct
5 Correct 28 ms 16252 KB Output is correct
6 Correct 25 ms 16204 KB Output is correct

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 41 ms 16092 KB Output is correct
2 Correct 40 ms 16132 KB Output is correct
3 Correct 543 ms 26184 KB Output is correct
4 Correct 519 ms 25636 KB Output is correct
5 Correct 561 ms 28336 KB Output is correct

Subtask #5
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 15952 KB Output is correct
2 Correct 41 ms 16092 KB Output is correct
3 Correct 40 ms 16132 KB Output is correct
4 Correct 44 ms 16516 KB Output is correct
5 Correct 28 ms 16252 KB Output is correct
6 Correct 25 ms 16204 KB Output is correct
7 Correct 543 ms 26184 KB Output is correct
8 Correct 519 ms 25636 KB Output is correct
9 Correct 561 ms 28336 KB Output is correct
10 Correct 559 ms 26416 KB Output is correct
11 Correct 507 ms 24748 KB Output is correct
12 Correct 548 ms 29388 KB Output is correct
13 Correct 585 ms 29292 KB Output is correct
14 Correct 533 ms 27216 KB Output is correct