Submission #540190

#	Time	Username	Problem	Language	Result	Execution time	Memory
540190		krit3379	Commuter Pass (JOI18_commuter_pass)	C++17	31 / 100	448 ms	35116 KiB

commuter_pass

#include<bits/stdc++.h>
using namespace std;
#define N 100005

struct A{
    long long a,w,st,tr;
    bool operator<(const A& o)const{
        return w>o.w;
    }
};

vector<vector<long long>> dis(2,vector<long long>(N,1e18)),dp(3,vector<long long>(N,1e18));
vector<A> g[N];
bitset<N> in;
priority_queue<A> q;

void dijk(int idx,int s){
    q.push({s,0});
    dis[idx][s]=0;
    while(!q.empty()){
        auto [a,w,st,tr]=q.top();
        q.pop();
        if(w>dis[idx][a])continue;
        for(auto x:g[a]){
            if(w+x.w<dis[idx][x.a])q.push({x.a,w+x.w}),dis[idx][x.a]=w+x.w;
        }
    }
}

int main(){
    int n,m,s,t,u,v,i,a,b;
    long long w,mi;
    scanf("%d %d %d %d %d %d",&n,&m,&s,&t,&u,&v);
    for(i=1;i<=m;i++){
        scanf("%d %d %lld",&a,&b,&w);
        g[a].push_back({b,w});
        g[b].push_back({a,w});
    }
    dijk(0,s);
    dijk(1,t);
    mi=dis[0][t];
    for(i=1;i<=n;i++)if(dis[0][i]+dis[1][i]==mi)in[i]=true;
    q.push({u,0,0,0});
    dp[0][u]=0;
    while(!q.empty()){
        auto [a,w,st,tr]=q.top();
        q.pop();
        if(w>dp[st][a])continue;
        if(st==0&&in[a]&&w<dp[1][a])q.push({a,w,1,0}),dp[1][a]=w;
        for(auto x:g[a]){
            if(st!=1&&w+x.w<dp[st][x.a])q.push({x.a,w+x.w,st,tr}),dp[st][x.a]=w+x.w;
            if(st==1&&w+x.w<dp[2][x.a])q.push({x.a,w+x.w,2,tr}),dp[2][x.a]=w+x.w;
            if(st==1&&in[x.a]&&abs(dis[0][a]-dis[0][x.a])==x.w&&w<dp[1][x.a]){
                if(!tr)q.push({x.a,w,1,(dis[0][a]-dis[0][x.a]>0)?1:-1}),dp[1][x.a]=w;
                else if(a!=s&&a!=t&&tr==1&&dis[0][a]-dis[0][x.a]>0)q.push({x.a,w,1,1}),dp[1][x.a]=w;
                else if(a!=s&&a!=t&&tr==-1&&dis[0][a]-dis[0][x.a]<0)q.push({x.a,w,1,-1}),dp[1][x.a]=w;
            }
        }
    }
    printf("%lld",min({dp[0][v],dp[1][v],dp[2][v]}));
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:33:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     scanf("%d %d %d %d %d %d",&n,&m,&s,&t,&u,&v);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:35:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         scanf("%d %d %lld",&a,&b,&w);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45