Submission #339723

#	Time	Username	Problem	Language	Result	Execution time	Memory
339723		talant117408	Crazy old lady (IZhO13_crazy)	C++17	0 / 100	1 ms	364 KiB

crazy

/*
    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 == 0 && 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;
}

• Subtask 1: 0 / 100