Submission #1063138

#	Time	Username	Problem	Language	Result	Execution time	Memory
1063138		Unforgettablepl	Railway Trip (JOI17_railway_trip)	C++17	20 / 100	2054 ms	13684 KiB

railway_trip

#include <bits/stdc++.h>
using namespace std;

#define int long long


int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n,k,q;
    cin >> n >> k >> q;
    vector<int> l(n+1);
    vector<vector<int>> idxes(k+1);
    for(int i=1;i<=n;i++)cin>>l[i];
    vector<vector<int>> adj(n+1);
    stack<pair<int,int>> s;
    for(int i=1;i<=n;i++) {
        while(!s.empty() and s.top().first<l[i])s.pop();
        if(!s.empty()) {
            adj[s.top().second].emplace_back(i);
            adj[i].emplace_back(s.top().second);
        }
        s.emplace(l[i],i);
    }
    while(!s.empty())s.pop();
    for(int i=n;i;i--){
        while(!s.empty() and s.top().first<l[i])s.pop();
        if(!s.empty()) {
            adj[s.top().second].emplace_back(i);
            adj[i].emplace_back(s.top().second);
        }
        s.emplace(l[i],i);
    }
    for(int i=1;i<=q;i++) {
        int a,b;
        cin >> a >> b;
        vector<bool> visited(n+1);
        queue<pair<int,int>> qu;
        qu.emplace(-1,a);
        while(!qu.empty()) {
            auto [dist,idx] = qu.front();qu.pop();
            if(visited[idx])continue;
            visited[idx]=true;
            if(idx==b) {
                cout << dist << '\n';
                break;
            }
            for(int&x:adj[idx])if(!visited[x])qu.emplace(dist+1,x);
        }
    }
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 0 / 25
• Subtask 4: 0 / 55