Submission #1096073

#	Time	Username	Problem	Language	Result	Execution time	Memory
1096073		alexdd	Climbers (RMI18_climbers)	C++17	55 / 100	2616 ms	524288 KiB

climbers

#include <bits/stdc++.h>
using namespace std;
const int MAX_STARI = 8300000;
const long long INF = 1e18;

vector<pair<int,int>> con[MAX_STARI];
long long dist[MAX_STARI];
int nrm[5005][5005],cate;
int n,p[5005];
void add_edge(int v1, int m1, int v2, int m2)
{
    con[nrm[v1][m1]].push_back({nrm[v2][m2],abs(p[v1]-p[v2])});
    con[nrm[v2][m2]].push_back({nrm[v1][m1],abs(p[v1]-p[v2])});
}
priority_queue<pair<long long,int>> pq;
signed main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>p[i];
    assert(p[1]==0);
    assert(p[n]==0);
    for(int v=1;v<=n;v++)
    {
        for(int m=1;m<n;m++)
        {
            if(p[v] < min(p[m],p[m+1]) || p[v] > max(p[m],p[m+1]))
                continue;
            nrm[v][m] = ++cate;
        }
    }
    for(int v=1;v<=n;v++)
    {
        for(int m=1;m<n;m++)
        {
            if(p[v] < min(p[m],p[m+1]) || p[v] > max(p[m],p[m+1]))
                continue;
            for(int newv:{v-1,v+1})
            {
                if(newv>=1 && newv<=n && min(p[m],p[m+1]) <= p[newv] && p[newv] <= max(p[m],p[m+1]))
                {
                    add_edge(v,m,newv,m);
                }
            }

            if(p[v] == p[m] && m-1>0)
            {
                add_edge(v,m,v,m-1);
            }
            if(p[v] == p[m+1] && m+1<n)
            {
                add_edge(v,m,v,m+1);
            }

            
            if(v+1<n && min(p[v],p[v+1]) <= p[m] && p[m] <= max(p[v],p[v+1]))
            {
                add_edge(v,m,m,v);
            }
            if(v-1>0 && min(p[v],p[v-1]) <= p[m] && p[m] <= max(p[v],p[v-1]))
            {
                add_edge(v,m,m,v-1);
            }
            if(v+1<n && min(p[v],p[v+1]) <= p[m+1] && p[m+1] <= max(p[v],p[v+1]))
            {
                add_edge(v,m,m+1,v);
            }
            if(v-1>0 && min(p[v],p[v-1]) <= p[m+1] && p[m+1] <= max(p[v],p[v-1]))
            {
                add_edge(v,m,m+1,v-1);
            }
        }
    }
    for(int i=1;i<=cate;i++)
        dist[i]=INF;
    dist[nrm[n][1]]=0;
    dist[nrm[1][n-1]]=0;
    pq.push({0,nrm[n][1]});
    pq.push({0,nrm[1][n-1]});
    while(!pq.empty())
    {
        long long cdist = -pq.top().first;
        int nod = pq.top().second;
        pq.pop();
        if(dist[nod]!=cdist)
            continue;
        //cerr<<nod<<" new dist "<<dist[nod]<<"\n";
        for(auto [adj,c]:con[nod])
        {
            if(cdist + c < dist[adj])
            {
                dist[adj] = cdist + c;
                pq.push({-dist[adj],adj});
            }
        }
    }
    long long rez=INF;
    for(int m=1;m<n;m++)
    {
        rez = min(rez, dist[nrm[m][m]]);
        rez = min(rez, dist[nrm[m+1][m]]);
    }
    assert(rez<INF);
    cout<<rez;
    return 0;
}
/*
7
0 10 1 20 5 10 0
*/

• Subtask 1: 15 / 25
• Subtask 2: 25 / 25
• Subtask 3: 15 / 50