/*
Code written by Talant I.D.
*/
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
//typedef tree <int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
#define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
inline bool isvowel(char ch){
ch = tolower(ch);
return (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u');
}
inline bool isprime(int n){
if(n < 2 || (n%2 == 0 && n != 2)) return false;
for(int i = 3; i*i <= n; i++)
if(n%i == 0) return false;
return true;
}
class Union{
private:
vector <int> saizu, link;
public:
Union(int n){
saizu.assign(n, 1); link.resize(n);
iota(all(link), 0);
}
int find(int n){
if(link[n] == n) return n;
return link[n] = find(link[n]);
}
int same(int a, int b){
return find(a) == find(b);
}
void unite(int a, int b){
if(same(a, b)) return;
a = find(a); b = find(b);
if(saizu[a] < saizu[b]) swap(a, b);
saizu[a] += saizu[b];
link[b] = a;
}
int getsize(int a){
return saizu[find(a)];
}
};
const int mod = 1e9+7;
ll mode(ll a){
a %= mod;
if(a < 0) a += mod;
return a;
}
ll subt(ll a, ll b){
return mode(mode(a)-mode(b));
}
ll add(ll a, ll b){
return mode(mode(a)+mode(b));
}
ll mult(ll a, ll b){
return mode(mode(a)*mode(b));
}
ll binpow(ll a, ll b){
ll res = 1;
while(b){
if(b&1) res = mult(res, a);
a = mult(a, a);
b >>= 1;
}
return res;
}
vector <vector <int>> graph;
int used[1007], cycles;
vector <int> vec, eligible;
void dfs(int v){
used[v] = 1;
vec.pb(v);
for(auto to : graph[v]){
if(used[to] == 1){
cycles++;
int little = 0;
int mn = vec[0];
for(int i = 1; i < sz(vec); i++){
mn = min(mn, vec[i]);
if(vec[i] < vec[i-1]){
little++;
}
}
if(little <= 1 && sz(vec) != 2){
eligible.pb(mn);
}
}
else if(used[to] == 0){
dfs(to);
}
}
used[v] = 2;
}
int main(){
do_not_disturb
int t;
cin >> t;
while(t--){
int n;
cin >> n;
graph.resize(n+1);
for(int i = 1; i <= n; i++){
used[i] = 0;
int x;
cin >> x;
if(x != i)
graph[i].pb(x);
}
cycles = 0;
for(int i = 1; i <= n; i++){
if(!used[i]){
dfs(i);
}
vec.clear();
}
if(sz(eligible) == 1 && cycles == 1){
cout << eligible[0] << endl;
}
else{
cout << 0 << endl;
}
eligible.clear();
graph.clear();
}
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
364 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
