제출 #643103

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
643103		mahatma_muhammad	Railway (BOI17_railway)	C++14	0 / 100	1092 ms	19020 KiB

railway

#include <bits/stdc++.h>
#include <math.h>
//in the name of god,aka allah
//**gray sety orz**
using namespace std;
#define pi pair<long long , long long>
#define pii pair<long long , pair<long long , long long>>
const int maxm = 5e5;
const long long mod = 1e9 + 7 ;
typedef long long ll;
ll l,r,mid;
ll n,m;
ll darage[maxm] , ss , mm;
queue<int> q;
bool vis[maxm];
ll pedaret[maxm];
set<string> st;
ll rp[maxm];
map<string,ll> mp;
inline void bfs(){
    mid = 0;
    while(q.size()){
        l = q.front(); 
        q.pop();
        mid++; 
        vis[l]=1;
        if(!vis[pedaret[l]]){           
            if(!vis[pedaret[pedaret[l]]]&&darage[pedaret[pedaret[l]]]-1==0) q.push(pedaret[pedaret[l]]);
            vis[pedaret[l]]=1;
        }
    }
    return;
}
int pe(string s){
    if(st.find(s)==st.end()) mp.insert({s,mp.size()}) , st.insert(s);
    return mp[s];
}
int main() {
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin>>n;
    if(n%2) return cout<<-1,0; 
    for(int i = 0; i<n; i++){
        string s,t;
        cin>>s>>t;
        l=pe(s);
        r=pe(t);
        pedaret[l]=r;
        darage[r]++;
    }
    for(int i=0; i<n; i++){
        if(pedaret[pedaret[i]]==i && pedaret[i]!=i){
            vis[i]=1,vis[pedaret[i]]=1;
        }  
    }
    for(int i=0; i<n; i++) {
        if(!vis[i] && darage[i]==0) q.push(i);
    }
    bfs();
    for(int i=0; i<n; i++){
        if(!vis[i]){
            r=1;
            ss=pedaret[i];
            while (ss!=i) r++ , ss=pedaret[ss];
            mid+=(r+1)/2;
        }
    }
    cout<<mid;
}

• Subtask 1: 0 / 8
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