Submission #210382

#	Time	Username	Problem	Language	Result	Execution time	Memory
210382		SamAnd	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	450 ms	33580 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define m_p make_pair
const int N = 200005;
struct ban
{
    int x;
    long long d;
    ban(){}
    ban(int x, long long d)
    {
        this->x = x;
        this->d = d;
    }
};
bool operator<(const ban& a, const ban& b)
{
    return a.d > b.d;
}

int n, m;
int s, t;
int u, v;
vector<ban> a[N];

long long ds[N], dt[N], du[N], dv[N];

bool c[N];
void djk(int x, long long d[])
{
    memset(c, false, sizeof c);
    priority_queue<ban> q;
    q.push(ban(x, 0));
    while (1)
    {
        ban t;
        do
        {
            if (q.empty())
                return;
            t = q.top();
            q.pop();
        } while(c[t.x]);
        c[t.x] = true;
        d[t.x] = t.d;
        for (int i = 0; i < a[t.x].size(); ++i)
        {
            ban h = a[t.x][i];
            h.d += t.d;
            if (!c[h.x])
                q.push(h);
        }
    }
}

vector<int> g[N];

long long ans;

long long minu[N], minv[N];
void dfs(int x)
{
    if (c[x])
        return;
    c[x] = true;
    minu[x] = du[x];
    minv[x] = dv[x];
    for (int i = 0; i < g[x].size(); ++i)
    {
        int h = g[x][i];
        dfs(h);
        minu[x] = min(minu[x], minu[h]);
        minv[x] = min(minv[x], minv[h]);
    }
    ans = min(ans, minu[x] + dv[x]);
    ans = min(ans, minv[x] + du[x]);
}

int main()
{
    scanf("%d%d", &n, &m);
    scanf("%d%d", &s, &t);
    scanf("%d%d", &v, &u);
    for (int i = 0; i < m; ++i)
    {
        int x, y, d;
        scanf("%d%d%d", &x, &y, &d);
        a[x].push_back(ban(y, d));
        a[y].push_back(ban(x, d));
    }
    djk(s, ds);
    djk(t, dt);
    djk(u, du);
    djk(v, dv);
    for (int x = 1; x <= n; ++x)
    {
        for (int i = 0; i < a[x].size(); ++i)
        {
            ban h = a[x][i];
            if (ds[x] + h.d + dt[h.x] == ds[t])
                g[x].push_back(h.x);
        }
    }
    ans = du[v];
    memset(c, false, sizeof c);
    dfs(s);
    printf("%lld\n", ans);
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void djk(int, long long int*)':
commuter_pass.cpp:46:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < a[t.x].size(); ++i)
                         ~~^~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'void dfs(int)':
commuter_pass.cpp:68:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < g[x].size(); ++i)
                     ~~^~~~~~~~~~~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:97:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < a[x].size(); ++i)
                         ~~^~~~~~~~~~~~~
commuter_pass.cpp:81:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
commuter_pass.cpp:82:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &s, &t);
     ~~~~~^~~~~~~~~~~~~~~~
commuter_pass.cpp:83:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &v, &u);
     ~~~~~^~~~~~~~~~~~~~~~
commuter_pass.cpp:87:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &x, &y, &d);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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