Submission #939296

#	Time	Username	Problem	Language	Result	Execution time	Memory
939296		vjudge1	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	343 ms	42192 KiB

commuter_pass

#include<bits/stdc++.h>

using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long ll;
#define int ll
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define mispertion ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define F first
#define S second
#define getlast(s) (*s.rbegin())
#define debg cout << "OK\n"

const ld PI = 3.1415926535;
const int N = 2e5 + 6;
const int M = 7e6 + 1;
const int mod = 1e9+7;
const int infi = INT_MAX;
const ll infl = LLONG_MAX;
const int P = 31;

int mult(int a, int b) {
    return a * 1LL * b % mod;
}

int sum(int a, int b) { 
    if (a + b < 0)
        return a + b + mod;
    if (a + b >= mod)
        return a + b - mod;
    return a + b;
}

ll binpow(ll a, ll n) {
    if (n == 0)
        return 1;
    if (n % 2 == 1) {
        return binpow(a, n - 1) * a % mod;
    } else {
        ll b = binpow(a, n / 2);
        return b * b % mod;
    }
}

vector<pii> g[N];
vector<int> ng[N], pss[N], poryadok;
int dfr[N], dto[N], ds[N];

void dfs(int v, vector<int> &used){
    used[v] = 1;
    for(auto u : pss[v]){
        ng[u].pb(v);
        if(!used[u])
            dfs(u, used);
    }
}

void dfs1(int v, vector<int> &used){
    used[v] = 1;
    for(auto u : ng[v]){
        if(!used[u])
            dfs1(u, used);
    }
    poryadok.pb(v);
}

void solve(){
    int n, m;
    cin >> n >> m;
    int s, t;
    cin >> s >> t;
    int fr, to;
    cin >> fr >> to;
    for(int i = 0; i < m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }
    set<pii> st;
    for(int i = 1; i <= n; i++)
        ds[i] = infl, dfr[i] = infl, dto[i] = infl;
    ds[s] = 0;
    st.insert({ds[s], s});
    while(!st.empty()){
        int v = (*st.begin()).S;
        st.erase(st.begin());
        for(auto e : g[v]){
            int u = e.F, w = e.S;
            if(ds[u] == ds[v] + w)
                pss[u].pb(v);
            if(ds[u] > ds[v] + w){
                st.erase({ds[u], u});
                ds[u] = ds[v] + w;
                pss[u].clear();
                pss[u].pb(v);
                st.insert({ds[u], u});
            }
        }
    }   
    dfr[fr] = 0;
    st.insert({dfr[fr], fr});
    while(!st.empty()){
        int v = (*st.begin()).S;
        st.erase(st.begin());
        for(auto e : g[v]){
            int u = e.F, w = e.S;
            if(dfr[u] > dfr[v] + w){
                st.erase({dfr[u], u});
                dfr[u] = dfr[v] + w;
                st.insert({dfr[u], u});
            }
        }
    } 
    dto[to] = 0;
    st.insert({dto[to], to});
    while(!st.empty()){
        int v = st.begin()->S;
        st.erase(st.begin());
        for(auto e : g[v]){
            int u = e.F, w = e.S;
            if(dto[u] > dto[v] + w){
                st.erase({dto[u], u});
                dto[u] = dto[v] + w;
                st.insert({dto[u], u});
            }
        }
    }  
    vector<int> used(n + 1, 0);
    dfs(t, used);
    used.assign(n + 1, 0);
    dfs1(s, used);
    reverse(all(poryadok));
    vector<int> mn(n + 1, infl);
    vector<int> mn1(n + 1, infl);
    for(int i = 1; i <= n; i++)
        mn[i] = dfr[i], mn1[i] = dto[i];
    int ans = dfr[to];
    for(auto v : poryadok){
        for(auto u : ng[v]){
            mn[u] = min(mn[u], mn[v]);
            mn1[u] = min(mn1[u], mn1[v]);
        }
        ans = min(ans, min(mn[v] + dto[v], mn1[v] + dfr[v]));
    }
    cout << ans << '\n';
}   

signed main() {
    mispertion;
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

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