Submission #682776

#	Time	Username	Problem	Language	Result	Execution time	Memory
682776		Paul_Liao_1457	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	1087 ms	3320 KiB

ho_t4

//記得跳題
#include<iostream>
#include<array>
#include<vector>
#include<string>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<math.h>
#include<map>
#include<unordered_map>
#include<cstring>
#include<iomanip>
#include<bitset>
#include<tuple>
 
#define ll long long
#define LL __int128_t
#define DB double
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a,b) for(int i=a;i>=b;i--)
#define pb push_back
#define mp make_pair
#define INF (ll)(2e9)
#define MOD (ll)(1e9+7)
#define F first
#define S second
#define endl "\n"
#define AC ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
using namespace std;

template<class T> using PQ=priority_queue<T,vector<T>,less<T> >;

void file(){
    freopen("/Users/liaoyunyang/Desktop/meta_in.txt","r",stdin);
    freopen("/Users/liaoyunyang/Desktop/meta_out.txt","w",stdout);
}

int s[200005],seg[800005];

void build(int id,int l,int r){
    if(l==r){
        seg[id]=s[l]; return;
    }
    int mid=(l+r)>>1;
    build(id*2,l,mid);
    build(id*2+1,mid+1,r);
    seg[id]=max(seg[id*2],seg[id*2+1]);
}

int ask(int id,int l,int r,int L,int R){
    if(l>R||r<L) return 0;
    if(L<=l&&r<=R) return seg[id];
    int mid=(l+r)>>1;
    return max(ask(id*2,l,mid,L,R),ask(id*2+1,mid+1,r,L,R));
}

vector<pair<int,int> > e[205];
int c[50005],d[50005],a[50005],b[50005];
bool vis[2][205];

signed main(){
    AC;
    int n,m; cin>>n>>m;
    FOR(i,0,m){
        cin>>a[i]>>b[i]>>c[i]>>d[i];
        e[a[i]].pb({b[i],i});
        e[b[i]].pb({a[i],i+m});
    }
    int ans=INF;
    queue<int> Q;
    Q.push(1); vis[0][1]=1;
    while(Q.size()){
        int now=Q.front(); Q.pop();
        for(auto k:e[now])if(!vis[0][k.F]&&k.S<m){
            vis[0][k.F]=1; Q.push(k.F);
        }
    }
    Q.push(n); vis[1][n]=1;
    while(Q.size()){
        int now=Q.front(); Q.pop();
        for(auto k:e[now])if(!vis[1][k.F]&&k.S<m){
            vis[1][k.F]=1; Q.push(k.F);
        }
    }
    if(vis[0][n]&&vis[1][1]){
        cout<<0<<endl; return 0;
    }
    FOR(i,0,m){
        FOR(j,1,n+1) vis[0][j]=vis[1][j]=0;
        queue<int> Q;
        Q.push(1); vis[0][1]=1;
        while(Q.size()){
            int now=Q.front(); Q.pop();
            for(auto k:e[now])if(!vis[0][k.F]&&k.S!=i&&(k.S<m||k.S==i+m)){
                vis[0][k.F]=1; Q.push(k.F);
            }
        }
        Q.push(n); vis[1][n]=1;
        while(Q.size()){
            int now=Q.front(); Q.pop();
            for(auto k:e[now])if(!vis[1][k.F]&&k.S!=i&&(k.S<m||k.S==i+m)){
                vis[1][k.F]=1; Q.push(k.F);
            }
        }
        if(vis[0][n]&&vis[1][1]){
            ans=min(ans,d[i]);
        }
    }
    if(ans==INF) cout<<-1<<endl;
    else cout<<ans<<endl;
}


/*

 */

Compilation message (stderr)

ho_t4.cpp: In function 'void file()':
ho_t4.cpp:37:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     freopen("/Users/liaoyunyang/Desktop/meta_in.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ho_t4.cpp:38:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     freopen("/Users/liaoyunyang/Desktop/meta_out.txt","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63