Submission #1241948

#	Time	Username	Problem	Language	Result	Execution time	Memory
1241948		sunit	Commuter Pass (JOI18_commuter_pass)	C++20	0 / 100	2096 ms	41452 KiB

commuter_pass

#include<bits/stdc++.h>
#define bl bool
#define db double 
#define fl float 
#define st string 
#define pb push_back
#define pf push_front
#define is insert
#define endl "\n"
#define pba pop_back
#define pfr pop_front
#define ub upper_bound
#define lb lower_bound 
#define fi first 
#define se second 
#define FOR(i, l, r, st) for(int i = l; i <= r; i += st)
#define FOS(i, l, r, sl) for(int i = l; i >= r; i -= sl)
#define mii map<int, int>
#define us unordered_set 
#define pii pair<int, int>
#define vt vector
using namespace std;

const int maxn = 1e6 + 5;
const int mod = 1e9 + 7;
const int INF = 1e18;

void suncuti() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
}

void fre() {
    if(fopen("name.INP", "r")) {
        freopen("name.INP", "r", stdin);
        freopen("name.OUT", "w", stdout);
    }
}

int n, m, A, B, C, D;
vt<pii> kt[maxn];
int trace[maxn];
set<pii> seen;
int dp[maxn], dp2[maxn];

void dij() {
    fill(dp, dp + n + 1, INF);
    memset(trace, -1, sizeof(trace));
    dp[A] = 0;
    priority_queue<pii, vt<pii>, greater<pii>> q;
    q.push({0, A});
    while(q.size()) {
        int c = q.top().fi, u = q.top().se;
        q.pop();
        if(c > dp[u]) continue;
        for(auto v : kt[u]) {
            int cost = v.se + dp[u];
            if(cost < dp[v.fi]) {
                dp[v.fi] = cost;
                trace[v.fi] = u;
                q.push({dp[v.fi], v.fi});
            }
        }
    }
}

vt<int> path;

void bfs() {
    fill(dp2, dp2 + n + 1, INF);
    dp2[C] = 0;
    deque<int> d;
    d.pf(C);
    while(d.size()) {
        int u = d.front(); d.pfr();
        for(auto v : kt[u]) {
            int cost = dp2[u];
            if(seen.count({u, v.fi}) || seen.count({v.fi, u})) cost = cost;
            else cost += v.se;
            if(cost < dp2[v.fi]) {
                dp2[v.fi] = cost;
                if(cost == dp2[u]) d.pf(v.fi);
                else d.pb(v.fi);
            }
        }
    }
}

main() {
    suncuti();

    cin >> n >> m;
    cin >> A >> B;
    cin >> C >> D;

    FOR(i, 1, m, 1) {
        int u, v, w;
        cin >> u >> v >> w;
        kt[u].pb({v, w});
        kt[v].pb({u, w});
    }

    dij();
    int kit = B;
    while(kit != -1) {
        path.pb(kit);
        kit = trace[kit];
    }
    reverse(path.begin(), path.end());

    FOR(i, 1, path.size() - 1, 1) {
        seen.is({path[i], path[i - 1]});
        seen.is({path[i - 1], path[i]});
    }

    bfs();
    cout << dp2[D];
}

Compilation message (stderr)

commuter_pass.cpp:26:17: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
   26 | const int INF = 1e18;
      |                 ^~~~
commuter_pass.cpp:90:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   90 | main() {
      | ^~~~
commuter_pass.cpp: In function 'void fre()':
commuter_pass.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen("name.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen("name.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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