結果

問題 No.1647 Travel in Mitaru city 2
ユーザー leaf_1415
提出日時 2021-08-13 21:52:47
言語 C++11（廃止可能性あり）
(gcc 13.3.0)
結果
AC  
実行時間 279 ms / 2,500 ms
コード長 9,042 bytes
コンパイル時間 2,064 ms
コンパイル使用メモリ 122,612 KB
実行使用メモリ 35,264 KB
最終ジャッジ日時 2024-10-13 03:14:05
合計ジャッジ時間 14,699 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 48
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ソースコード

diff #
プレゼンテーションモードにする

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#include <complex>
#include <unordered_set>
#include <unordered_map>
#define rep(x, s, t) for(ll x = (s); (x) <= (t); (x)++)
#define per(x, s, t) for(ll x = (s); (x) >= (t); (x)--)
#define reps(x, s) for(ll x = 0; (x) < (ll)(s).size(); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define sz(x) ((ll)(x).size())
#define ceil(x, y) (((x)+(y)-1) / (y))
#define all(x) (x).begin(),(x).end()
#define outl(...) dump_func(__VA_ARGS__)
#define outf(x) cout << fixed << setprecision(16) << (x) << endl
#define inf 1e18
const double PI = 3.1415926535897932384626433;
using namespace std;
typedef long long llint;
typedef long long ll;
typedef pair<ll, ll> P;
struct edge{
    ll to, cost;
    edge(){}
    edge(ll a, ll b){ to = a, cost = b;}
};
const ll dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
//const ll mod = 1000000007;
const ll mod = 998244353;
struct mint{
    ll x = 0;
    mint(ll y = 0){x = y; if(x < 0 || x >= mod) x = (x%mod+mod)%mod;}
    mint(const mint &ope) {x = ope.x;}
    
    mint operator-(){return mint(-x);}
    mint operator+(const mint &ope){return mint(x) += ope;}
    mint operator-(const mint &ope){return mint(x) -= ope;}
    mint operator*(const mint &ope){return mint(x) *= ope;}
    mint operator/(const mint &ope){return mint(x) /= ope;}
    mint& operator+=(const mint &ope){
        x += ope.x;
        if(x >= mod) x -= mod;
        return *this;
    }
    mint& operator-=(const mint &ope){
        x += mod - ope.x;
        if(x >= mod) x -= mod;
        return *this;
    }
    mint& operator*=(const mint &ope){
        x *= ope.x, x %= mod;
        return *this;
    }
    mint& operator/=(const mint &ope){
        ll n = mod-2; mint mul = ope;
        while(n){
            if(n & 1) *this *= mul;
            mul *= mul;
            n >>= 1;
        }
        return *this;
    }
    mint inverse(){return mint(1) / *this;}
    bool operator ==(const mint &ope){return x == ope.x;}
    bool operator !=(const mint &ope){return x != ope.x;}
    bool operator <(const mint &ope){return x < ope.x;}
};
mint modpow(mint a, ll n){
    if(n == 0) return mint(1);
    if(n % 2) return a * modpow(a, n-1);
    else return modpow(a*a, n/2);
}
istream& operator >>(istream &is, mint &ope){
    ll t; is >> t, ope.x = t;
    return is;
}
ostream& operator <<(ostream &os, mint &ope){return os << ope.x;}
ostream& operator <<(ostream &os, const mint &ope){return os << ope.x;}
vector<mint> fact, fact_inv;
void make_fact(int n){
    fact.resize(n+1), fact_inv.resize(n+1);
    fact[0] = mint(1); rep(i, 1, n) fact[i] = fact[i-1] * mint(i);
    fact_inv[n] = fact[n].inverse(); per(i, n-1, 0) fact_inv[i] = fact_inv[i+1] * mint(i+1);
}
mint comb(ll n, ll k){ if(n < 0 || k < 0 || n < k) return mint(0); return fact[n] * fact_inv[k] * fact_inv[n-k];}
mint perm(ll n, ll k){ return comb(n, k) * fact[k]; }
vector<int> prime, pvec;
void make_prime(int n){
    prime.resize(n+1);
    rep(i, 2, n){
        if(prime[i]) continue;
        for(int j = i; j <= n; j+=i) prime[j] = i;
    }
    rep(i, 2, n) if(prime[i] == i) pvec.push_back(i);
}
bool exceed(ll x, ll y, ll m){return x >= m / y + 1;}
void mark(){ cout << "*" << endl; }
void yes(){ cout << "YES" << endl; }
void no(){ cout << "NO" << endl; }
ll sgn(ll x){ if(x > 0) return 1; if(x < 0) return -1; return 0;}
ll gcd(ll a, ll b){if(b == 0) return a; return gcd(b, a%b);}
ll lcm(ll a, ll b){return a/gcd(a, b)*b;}
ll digitnum(ll x, ll b = 10){ll ret = 0; for(; x; x /= b) ret++; return ret;}
ll digitsum(ll x, ll b = 10){ll ret = 0; for(; x; x /= b) ret += x % b; return ret;}
string lltos(ll x){string ret; for(;x;x/=10) ret += x % 10 + '0'; reverse(ret.begin(), ret.end()); return ret;}
ll stoll(string &s){ll ret = 0; for(auto c : s) ret *= 10, ret += c - '0'; return ret;}
template<typename T>
void uniq(T &vec){ sort(vec.begin(), vec.end()); vec.erase(unique(vec.begin(), vec.end()), vec.end());}
template<class S, class T> pair<S, T>& operator+=(pair<S,T> &s, const pair<S,T> &t){
    s.first += t.first, s.second += t.second;
    return s;
}
template<class S, class T> pair<S, T>& operator-=(pair<S,T> &s, const pair<S,T> &t){
    s.first -= t.first, s.second -= t.second;
    return s;
}
template<class S, class T> pair<S, T> operator+(const pair<S,T> &s, const pair<S,T> &t){
    return pair<S,T>(s.first+t.first, s.second+t.second);
}
template<class S, class T> pair<S, T> operator-(const pair<S,T> &s, const pair<S,T> &t){
    return pair<S,T>(s.first-t.first, s.second-t.second);
}
template<typename T>
ostream& operator << (ostream& os, vector<T>& vec) {
    for(int i = 0; i < vec.size(); i++) os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    return os;
}
template<typename T>
ostream& operator << (ostream& os, deque<T>& deq) {
    for(int i = 0; i < deq.size(); i++) os << deq[i] << (i + 1 == deq.size() ? "" : " ");
    return os;
}
template<typename T, typename U>
ostream& operator << (ostream& os, pair<T, U>& pair_var) {
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}
template<typename T, typename U>
ostream& operator << (ostream& os, const pair<T, U>& pair_var) {
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}
template<typename T, typename U>
ostream& operator << (ostream& os, map<T, U>& map_var) {
    for(typename map<T, U>::iterator itr = map_var.begin(); itr != map_var.end(); itr++) {
        os << "(" << itr->first << ", " << itr->second << ")";
        itr++; if(itr != map_var.end()) os << ","; itr--;
    }
    return os;
}
template<typename T>
ostream& operator << (ostream& os, set<T>& set_var) {
    for(typename set<T>::iterator itr = set_var.begin(); itr != set_var.end(); itr++) {
        os << *itr; ++itr; if(itr != set_var.end()) os << " "; itr--;
    }
    return os;
}
template<typename T>
ostream& operator << (ostream& os, multiset<T>& set_var) {
    for(typename multiset<T>::iterator itr = set_var.begin(); itr != set_var.end(); itr++) {
        os << *itr; ++itr; if(itr != set_var.end()) os << " "; itr--;
    }
    return os;
}
template<typename T>
void outa(T a[], ll s, ll t){for(ll i = s; i <= t; i++){ cout << a[i]; if(i < t) cout << " ";}cout << endl;}
void dump_func(){cout << endl;}
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&... tail) {
    cout << head;
    if(sizeof...(Tail) > 0) cout << " ";
    dump_func(std::move(tail)...);
}
struct DetectCycle{
    struct edge{
        int to, id;
        edge(){}
        edge(int a, int b){to = a, id = b;}
    };
    int n;
    vector<vector<edge> > G;
    vector<int> used;
    int eid;
    
    DetectCycle(){}
    DetectCycle(int n){init(n);}
    void init(int n){
        this->n = n;
        G.resize(n+1); for(int i = 0; i <= n; i++) G[i].clear();
        used.resize(n+1); for(int i = 0; i <= n; i++) used[i] = 0;
        eid = 0;
    }
    void add_edge(int u, int v){
        eid++;
        G[u].push_back(edge(v, eid));
        if(u != v) G[v].push_back(edge(u, eid));
    }
    int dfs(int v, int eid, vector<ll> &dest)
    {
        used[v] = 1;
        for(auto e : G[v]){
            int u = e.to, id = e.id;
            if(id == eid) continue;
            if(used[u]){
                dest.push_back(v);
                if(u == v) return -1;
                return u;
            }
            int res = dfs(u, id, dest);
            if(res == -1) return -1;
            if(res == -2) continue;
            dest.push_back(v);
            if(v == res) return -1;
            else return res;
        }
        return -2;
    }
    bool getCycle(int v, vector<ll> &dest){ //頂点vを含む連結成分のcycleの頂点を順番にdestに格納。戻り値はcycleの有無
        dest.clear();
        return dfs(v, -1, dest) == -1;
    }
};
struct UnionFind{
    int size;
    vector<int> parent;
    vector<int> rank;
    vector<llint> v, e;
    
    UnionFind(){}
    UnionFind(int size){
        this->size = size;
        parent.resize(size+1);
        rank.resize(size+1);
        v.resize(size+1);
        e.resize(size+1);
        init();
    }
    void init(){
        for(int i = 0; i <= size; i++){
            parent[i] = i, rank[i] = 0;
            v[i] = 1, e[i] = 0;
        }
    }
    int root(int i){
        if(parent[i] == i) return i;
        return parent[i] = root(parent[i]);
    }
    bool same(int i, int j){
        return root(i) == root(j);
    }
    void merge(int i, int j){ // j will become new root
        parent[i] = j;
        v[j] += v[i];
        e[j] += e[i] + 1;
    }
    void unite(int i, int j){
        int root_i = root(i), root_j = root(j);
        if(root_i == root_j){
            e[root_i]++;
            return;
        }
        if(rank[root_i] < rank[root_j]) merge(root_i, root_j);
        else merge(root_j, root_i);
        if(rank[root_i] == rank[root_j]) rank[root_i]++;
    }
};
ll h, w, n;
map<P, ll> mp;
UnionFind uf(200005);
int main(void)
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> h >> w >> n;
    DetectCycle dt(h+w);
    
    ll u, v;
    rep(i, 1, n){
        cin >> u >> v;
        dt.add_edge(u, h+v);
        uf.unite(u, h+v);
        mp[P(u, v+h)] = mp[P(v+h, u)] = i;
    }
    
    vector<ll> vec;
    rep(i, 1, h+w){
        if(uf.root(i) != i) continue;
        if(dt.getCycle(i, vec)) break;
    }
    
    if(sz(vec) == 0){
        outl(-1);
        return 0;
    }
    
    if(vec[0] > h){
        vec.push_back(vec[0]);
        vec.erase(vec.begin());
    }
    vector<ll> ans;
    reps(i, vec) ans.push_back(mp[P(vec[i], vec[(i+1)%sz(vec)])]);
    
    outl(sz(ans));
    outl(ans);
    
    return 0;
}
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