Submission #896475

#	Time	Username	Problem	Language	Result	Execution time	Memory
896475		Unforgettablepl	Olympic Bus (JOI20_ho_t4)	C++17	37 / 100	1099 ms	5596 KiB

ho_t4

#pragma GCC optimize "Ofast"
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
/*
ID: samikgo1
TASK:
LANG: C++
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef complex<ll> point;
#define X real()
#define Y imag()
#define all(x) x.begin(),x.end()
#define allr(x) x.rbegin(),x.rend()
//#define f first
//#define s second
//#define x first
//#define y second
const ll INF = 1e17;
const ll sqrtn = 440;
const ll modulo = 1e9+7;
const ll siz = 262144;
const ll hashp = 923981238;
const ll hashm = 932439994;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
//#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>

#define int ll

struct edge{
    int u,v,c,d;
};

edge edgelist[50001];
set<int> adj[201];
int dist[201][201];
bool visited[201];
int n;

inline int dijkastra(){
    priority_queue<pair<int,int>,vector<pair<int,int>>,greater<>> q;
    int c1 = INF;
    q.emplace(0,1);
    while(!q.empty()){
        auto curr = q.top();q.pop();
        if(visited[curr.second])continue;
        if(curr.second==n){c1=curr.first;break;}
        visited[curr.second]=true;
        for(auto&i:adj[curr.second])if(!visited[edgelist[i].v])q.emplace(edgelist[i].c+curr.first,edgelist[i].v);
    }
    while(!q.empty())q.pop();
    for(bool&i:visited)i=false;
    int c2 = INF;
    q.emplace(0,n);
    while(!q.empty()){
        auto curr = q.top();q.pop();
        if(visited[curr.second])continue;
        if(curr.second==1){c2=curr.first;break;}
        visited[curr.second]=true;
        for(auto&i:adj[curr.second])if(!visited[edgelist[i].v])q.emplace(edgelist[i].c+curr.first,edgelist[i].v);
    }
    while(!q.empty())q.pop();
    for(bool&i:visited)i=false;
    return c1+c2;
}

void solve() {
    int m;
    cin >> n >> m;
    for(int i=1;i<=n;i++)for(int j=1;j<=n;j++)if(i!=j)dist[i][j]=INF;
    for(int i=1;i<=m;i++){
        cin >> edgelist[i].u >> edgelist[i].v >> edgelist[i].c >> edgelist[i].d;
        adj[edgelist[i].u].insert(i);
        dist[edgelist[i].u][edgelist[i].v] = min(dist[edgelist[i].u][edgelist[i].v],edgelist[i].c);
    }
    for(int k=1;k<=n;k++){
        for(int i=1;i<=n;i++){
            for(int j=1;j<=n;j++){
                dist[i][j] = min(dist[i][j],dist[i][k]+dist[k][j]);
            }
        }
    }
    int ans = dijkastra();
    for(int i=1;i<=m;i++){
        auto curr = edgelist[i];
        if(min(dist[1][n],dist[1][curr.v]+dist[curr.u][n])+min(dist[n][1],dist[n][curr.v]+dist[curr.u][1])+curr.d<ans){
            adj[curr.u].erase(i);
            adj[curr.v].insert(i);
            swap(edgelist[i].u,edgelist[i].v);
            ans = min(ans,dijkastra()+curr.d);
            adj[curr.v].erase(i);
            adj[curr.u].insert(i);
            swap(edgelist[i].u,edgelist[i].v);
        }
    }
    cout << (ans>=INF ? -1 : ans)<< '\n';
}

int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
//    freopen("mock.txt","r",stdin);
//    freopen(".out","w",stdout);
//    int t;
//    cin >> t;
//    while(t--)
    solve();
}

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