Submission #471857

#	Time	Username	Problem	Language	Result	Execution time	Memory
471857		FatihSolak	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	109 ms	13504 KiB

ho_t4

#include <bits/stdc++.h>
#define N 205
#define M 50005
#define int long long
using namespace std;
struct edge{
    int u,v,c,d,i;
};
vector<edge> edges(M);
vector<edge> adj[N];
int dp[N][N],dp2[N][N],dp3[N][N];
vector<pair<int,int>> dijkstra(int st,int nd){
    vector<int> dist(N,1e18);
    vector<pair<int,int>> par(N);
    dist[st] = 0;
    priority_queue<pair<int,int>> q;
    q.push({0,st});
    while(q.size()){
        auto tp = q.top();
        q.pop();
        tp.first *=-1;
        if(tp.second == nd){
            vector<pair<int,int>> path;
            int now = nd;
            path.push_back({nd,0});
            while(now != st){
                path.push_back(par[now]);
                now = par[now].first;
            }
            reverse(path.begin(),path.end());
            return path;
        }
        if(tp.first != dist[tp.second])continue;
        for(auto u:adj[tp.second]){
            if(dist[u.v] > dist[u.u] + u.c){
                dist[u.v] = dist[u.u] + u.c;
                par[u.v] = {u.u,u.i};
                q.push({-dist[u.v],u.v});
            }
        }
    }
    return {};
}
void solve(){
    int n,m;
    cin >> n >> m;
    for(int i=1;i<=m;i++){
        int u,v,c,d;
        cin >> u >> v >> c >> d;
        adj[u].push_back({u,v,c,d,i});
        edges[i] = {u,v,c,d};
    }
    auto path1 = dijkstra(1,n);
    auto path2 = dijkstra(n,1);
    map<int,int> mp1,mp2;
    for(int i = 0;i<(int)path1.size()-1;i++){
        mp1[path1[i].second] = i+1;
    }
    for(int i = 0;i<(int)path2.size()-1;i++){
        mp2[path2[i].second] = i+1;
    }
    for(int i=0;i<N;i++){
        for(int j=0;j<N;j++){
            dp[i][j] = dp2[i][j] = dp3[i][j] = 1e18;
        }
        dp[i][i] = dp2[i][i] = dp3[i][i] = 0;
    }
    for(int i=1;i<=m;i++){
        dp[edges[i].u][edges[i].v] = min(dp[edges[i].u][edges[i].v],edges[i].c);
        if(!mp1[i]){
            dp2[edges[i].u][edges[i].v] = min(dp2[edges[i].u][edges[i].v],edges[i].c);
        }
        if(!mp2[i]){
            dp3[edges[i].u][edges[i].v] = min(dp3[edges[i].u][edges[i].v],edges[i].c);
        }
    }
    for(int x=1;x<=n;x++){
        for(int i=1;i<=n;i++){
            for(int j=1;j<=n;j++){
                dp[i][j] = min(dp[i][j],dp[i][x] + dp[x][j]);
                dp2[i][j] = min(dp2[i][j],dp2[i][x] + dp2[x][j]);
                dp3[i][j] = min(dp3[i][j],dp3[i][x] + dp3[x][j]);
            }
        }
    }
    int ans = 1e18;
    ans = min(ans,dp[1][n] + dp[n][1]);
    for(int i=1;i<=m;i++){
        int now = edges[i].d;
        if(mp1[i]){
            int mini = 1e18;
            for(int l=0;l<=mp1[i]-1;l++){
                for(int r = mp1[i];r<path1.size();r++){
                    int x = path1[l].first;
                    int y = path1[r].first;
                    mini = min(mini, dp[1][x] + dp2[x][y] + dp[y][n]);
                }
            }
            now += mini;
        }
        else{
            now += min(dp[1][n],dp[1][edges[i].v] + edges[i].c + dp[edges[i].u][n]);
        }
        if(mp2[i]){
            int mini = 1e18;
            for(int l=0;l<=mp2[i]-1;l++){
                for(int r = mp2[i];r<path2.size();r++){
                    int x = path2[l].first;
                    int y = path2[r].first;
                    mini = min(mini, dp[n][x] + dp3[x][y] + dp[y][1]);
                }
            }
            now += mini;
        }
        else{
            now += min(dp[n][1],dp[n][edges[i].v] + edges[i].c + dp[edges[i].u][1]);
        }
        ans = min(ans,now);
    }
    cout << (ans < 1e18?ans:-1);
}

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    #ifdef Local
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
    #endif
    int t=1;
    //cin>>t;
    while(t--){
        solve();
    }
    #ifdef Local
    cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
    #endif
}

Compilation message (stderr)

ho_t4.cpp: In function 'void solve()':
ho_t4.cpp:93:37: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |                 for(int r = mp1[i];r<path1.size();r++){
      |                                    ~^~~~~~~~~~~~~
ho_t4.cpp:107:37: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  107 |                 for(int r = mp2[i];r<path2.size();r++){
      |                                    ~^~~~~~~~~~~~~

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