Submission #1318623

#TimeUsernameProblemLanguageResultExecution timeMemory
1318623dex111222333444555Commuter Pass (JOI18_commuter_pass)C++20
100 / 100
232 ms21000 KiB
#include <bits/stdc++.h>
#define all(v) begin(v), end(v)
#define ii pair<int, int>
#define fi first
#define se second
#define siz(v) (int)(v).size()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(i) (1LL << (i))
#define lli pair<long long, int>

using namespace std;

template<class X, class Y> bool minimize(X &x, const Y &y){return x > y ? x = y, 1: 0;}
template<class X, class Y> bool maximize(X &x, const Y &y){return x < y ? x = y, 1: 0;}

const int infINT = 1e9 + 243, MAXN = 1e5 + 5, mod = 20240131;
const long long inf = 1e18 + 234;

void add(int &a, const int &b){
    a += b;
    if (a >= mod) a -= mod;
}

int mul(const int &a, const int &b){
    return 1LL * a * 1LL * b % mod;
}

struct E{
    int u, v, w;

    E (int _u = 0, int _v = 0, int _w = 0):
        u(_u), v(_v), w(_w) {};
};

int numNode, numEdge, S, T, U, V, in[MAXN], preIn[MAXN];
long long distS[MAXN], distT[MAXN], distU[MAXN], distV[MAXN], res, dp[MAXN];
vector<ii> adj[MAXN];
vector<int> g[MAXN];
E edge[MAXN << 1];

void input(){
    cin >> numNode >> numEdge;
    cin >> S >> T >> U >> V;
    for(int i = 1; i <= numEdge; i++){
        int u, v, w; cin >> u >> v >> w;
        adj[u].emplace_back(v, w);
        adj[v].emplace_back(u, w);
        edge[i] = E(u, v, w);
    }
}

#define PUSH(u, d) if (minimize(dist[u], d)) q.push(lli(d, u))

void dijsktra(const int &sta, long long dist[MAXN]){
    memset(dist, 0x3f, (numNode + 1) * sizeof(long long));
    priority_queue<lli, vector<lli>, greater<lli> > q;
    PUSH(sta, 0);

    while(q.size()){
        long long len = q.top().fi;
        int u = q.top().se;
        q.pop();
        if (len > dist[u]) continue;
        for(ii x: adj[u]){
            int v = x.fi, w = x.se;
            PUSH(v, dist[u] + w);
        }
    }
}

void addEdge(int u, int v){
    g[u].push_back(v);
    in[v]++;
}

void bfs(long long distU[MAXN], long long distV[MAXN]){
    queue<int> q;
    for(int i = 1; i <= numNode; i++) if (!in[i]) q.push(i);

    while(q.size()){
        int u = q.front();
        minimize(dp[u], distU[u]);
        q.pop();
        minimize(res, dp[u] + distV[u]);
        for(int v: g[u]){
            minimize(dp[v], dp[u]);
            if (--in[v] == 0) q.push(v);
        }
    }
}

void solve(){
    dijsktra(S, distS);
    dijsktra(T, distT);
    dijsktra(U, distU);
    dijsktra(V, distV);

    res = distV[U];

    for(int i = 1; i <= numEdge; i++){
        int u = edge[i].u, v = edge[i].v, w = edge[i].w;
        if (distS[u] + w + distT[v] == distT[S]) addEdge(u, v);
        else if (distS[v] + w + distT[u] == distT[S]) addEdge(v, u);
    }

    for(int i = 1; i <= numNode; i++) preIn[i] = in[i];

    memset(dp, 0x3f, sizeof dp);
    bfs(distU, distV);

    for(int i = 1; i <= numNode; i++) in[i] = preIn[i];
    memset(dp, 0x3f, sizeof dp);
    bfs(distV, distU);

    cout << res << '\n';
}

signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    #define task "test"
    if (fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    input();
    solve();
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:122:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  122 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:123:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  123 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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