Submission #610712

#	Time	Username	Problem	Language	Result	Execution time	Memory
610712		nohaxjustsoflo	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	57 / 100	1093 ms	57628 KiB

skyscraper

#include <bits/stdc++.h>
#include <iostream>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<ll,null_type,less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> order_set;
mt19937 mt_rand(chrono::high_resolution_clock::now().time_since_epoch().count());
//uniform_int_distribution<int> gen; ///(min, max)
//int random() {return gen(mt_rand);}
const int mxN=30001;
const int mod=998244353;
const int mxlogN=40;
const int mxK=26;
const int inf=1e9;
const int K=600;
vector<int> who[mxN];
int n, m, a[mxN], b[mxN];
int id(int x, int p)
{
    return p*n+x;
}
pair<int,int> rev(int i)
{
    return {i%n,i/n};
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    for(int i=0; i<m; i++) cin >> a[i] >> b[i];
    for(int i=1; i<m; i++) who[a[i]].push_back(i);
    vector<int> q, q2;
    set<int> vis;
    q.push_back(id(a[0],b[0]));
    vis.insert(id(a[0],b[0]));
    int d=0;
    while(q.size())
    {
        for(int pos:q)
        {
            auto par=rev(pos);
            int x=par.first, p=par.second;
            while(who[x].size())
            {
                int j=who[x].back(); who[x].pop_back();
                if(j==1)
                {
                    cout << d << "\n";
                    return 0;
                }
                int id2=id(a[j],b[j]);
                if(!vis.count(id2))
                {
                    q2.push_back(id2);
                    vis.insert(id2);
                }
            }
        }
        while(q2.size())
        {
            q.push_back(q2.back());
            q2.pop_back();
        }
        for(int pos:q)
        {
            auto par=rev(pos);
            int x=par.first, p=par.second;
            int id2;
            if(x-p>=0)
            {
                id2=id(x-p,p);
                if(!vis.count(id2))
                {
                    q2.push_back(id2);
                    vis.insert(id2);
                }
            }
            if(x+p<n)
            {
                id2=id(x+p,p);
                if(!vis.count(id2))
                {
                    q2.push_back(id2);
                    vis.insert(id2);
                }
            }
        }
        q=q2;
        q2.clear();
        d++;
    }
    cout << "-1" << "\n";
    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:48:30: warning: unused variable 'p' [-Wunused-variable]
   48 |             int x=par.first, p=par.second;
      |                              ^

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 0 / 43