Submission #1105615

#	Time	Username	Problem	Language	Result	Execution time	Memory
1105615		12345678	Airplane (NOI23_airplane)	C++17	100 / 100	202 ms	25824 KiB

Main

#include <bits/stdc++.h>

using namespace std;

const int nx=2e5+5;

int n, m, a[nx], u, v, vl[nx], rvl[nx], l[nx], rl[nx], vs[nx];
vector<int> d[nx];
pair<int, int> res={1e9, 0};
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n>>m;
    for (int i=1; i<=n; i++) cin>>a[i], vl[i]=rvl[i]=l[i]=rl[i]=1e9;
    for (int i=1; i<=m; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u); 
    vl[1]=rvl[n]=l[1]=rl[n]=0;
    pq.push({0, 1});
    while (!pq.empty())
    {
        auto [cw, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto v:d[u]) if (vl[v]>max(cw+1, a[v])) l[v]=l[u]>a[v]?l[u]-1:a[v], vl[v]=max(cw+1, a[v]), pq.push({vl[v], v});
    }
    pq.push({0, n});
    for (int i=1; i<=n; i++) vs[i]=0;
    while (!pq.empty())
    {
        auto [cw, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto v:d[u]) if (rvl[v]>max(cw+1, a[v])) rl[v]=rl[u]>a[v]?rl[u]-1:a[v], rvl[v]=max(cw+1, a[v]), pq.push({rvl[v], v});
    }
    /*
    pq.push({0, 1});
    for (int i=1; i<=n; i++) vs[i]=0;
    while (!pq.empty())
    {
        auto [cw, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto v:d[u]) 
        {
            int cst=l[u]>a[v]?l[u]-1:a[v];
            if (l[v]>cst) l[v]=cst, pq.push({l[v], v});
        }
    }
    pq.push({0, n});
    for (int i=1; i<=n; i++) vs[i]=0;
    while (!pq.empty())
    {
        auto [cw, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto v:d[u]) 
        {
            int cst=rl[u]>a[v]?rl[u]-1:a[v];
            if (rl[v]>cst) rl[v]=cst, pq.push({rl[v], v});
        }
    }*/
    for (int i=1; i<=n; i++)
    {
        if (vl[i]<rl[i]) res=min(res, {vl[i]+rvl[i]+rl[i]-vl[i], i});
        else if (rvl[i]<l[i]) res=min(res, {vl[i]+rvl[i]+l[i]-rvl[i], i});
        else res=min(res, {vl[i]+rvl[i], i});
    }
    /*
    cout<<"vl ";
    for (int i=1; i<=n; i++) cout<<vl[i]<<' ';
    cout<<'\n';
    cout<<"rvl ";
    for (int i=1; i<=n; i++) cout<<rvl[i]<<' ';
    cout<<'\n';
    cout<<"l ";
    for (int i=1; i<=n; i++) cout<<l[i]<<' ';
    cout<<'\n';
    cout<<"rl ";
    for (int i=1; i<=n; i++) cout<<rl[i]<<' ';
    cout<<'\n';
    */
    cout<<res.first;
}

• Subtask 1: 22 / 22
• Subtask 2: 10 / 10
• Subtask 3: 31 / 31
• Subtask 4: 37 / 37