Submission #885922

#	Time	Username	Problem	Language	Result	Execution time	Memory
885922		Requiem	Robot (JOI21_ho_t4)	C++17	100 / 100	668 ms	98348 KiB

Main

#include<bits/stdc++.h>
// #define int long long
#define ll long long
#define pb push_back
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define MOD 1000000007
#define INF 1e18
#define fi first
#define se second
#define endl "\n"
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define sz(a) ((int)(a).size())
#define pi 3.14159265359
#define TASKNAME "robot"
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; } 
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; } 
using namespace std; 
typedef pair<ll,ll> ii; 
typedef pair<ll,ii> iii; 
typedef vector<ll> vi; 
const int MAXN = 1e5 + 9;
unordered_map<int,vector<iii>> g[MAXN];
unordered_map<int,ll> psum[MAXN];
ll dist[MAXN],n,m;
unordered_map<int,ll> dp[MAXN];
//dp[i]: khoang cach ngan nhat den dinh i.
//dp2[i][c]: khoang cach ngan nhat den i sao cho:
/*
- Ta di qua mot canh co mau c.
- Ta chua to mau lai canh do.
- Ta se roi dinh i de di den 1 dinh khac co mau c va ta se to mau lai cac neighbor cua no.
*/
main() 
{ 
    fast; 
   if (fopen(TASKNAME".inp","r")){
        freopen(TASKNAME".inp","r",stdin); 
        freopen(TASKNAME".out","w",stdout); 
   }
   cin>>n>>m;
   for(int i=1;i<=m;i++){
       int u,v,w,c,p;
       cin>>u>>v>>c>>p;
       g[u][c].pb({v,{c,p}});
       g[v][c].pb({u,{c,p}});
       psum[u][c] += p;
       psum[v][c] += p;
   } 
   priority_queue<tuple<ll,int,int>> pq;
   memset(dist,0x3f,sizeof(dist));
   dist[1] = 0;
   pq.push({0,1,0});
    while(!pq.empty()){
        ll du,u,c;
        tie(du,u,c) = pq.top();
        // cerr<<du<<' '<<u<<' '<<c<<endl;
        pq.pop();
        if (c){
            if (dp[u][c] < -du) continue;
            ll v,color,w,cost;
            for(iii e: g[u][c]){
                v = e.fi;
                color = e.se.fi;
                w = e.se.se;
                cost = -du + psum[u][color] - w;
                //we flip i.
                if (dist[v] > cost){
                    dist[v] = cost;
                    pq.push({-dist[v],v,0});
                }
            }
        }
        else{
            if (dist[u] < -du) continue;
            ll v,color,w,cost;
            for(auto &i: g[u]){
                for(iii e: i.se){
                    v = e.fi;
                    color = e.se.fi;
                    w = e.se.se;
                    // cout<<v<<' '<<color<<' '<<w<<endl;
                    cost = -du + psum[u][color] - w;
                    if (dist[v] > cost){
                        dist[v] = cost;
                        pq.push({-dist[v],v,0});
                    }

                    cost = -du + w;
                    if (dist[v] > cost){
                        dist[v] = cost;
                        pq.push({-dist[v],v,0});
                    }

                    cost = -du;
                    if (!dp[v].count(color) or dp[v][color] > cost){
                        dp[v][color] = cost;
                        pq.push({-dp[v][color],v,color});
                    }

                }
            }
        }
    }
    cout<<((dist[n] >= INF) ? -1 : dist[n])<<endl;
    exit(0);
} 

Compilation message (stderr)

Main.cpp:34:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   34 | main()
      | ^~~~
Main.cpp: In function 'int main()':
Main.cpp:43:16: warning: unused variable 'w' [-Wunused-variable]
   43 |        int u,v,w,c,p;
      |                ^
Main.cpp:38:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         freopen(TASKNAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:39:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |         freopen(TASKNAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 34 / 34
• Subtask 2: 24 / 24
• Subtask 3: 42 / 42