Submission #959204

#	Time	Username	Problem	Language	Result	Execution time	Memory
959204		Abito	Railway Trip (JOI17_railway_trip)	C++17	20 / 100	2091 ms	14936 KiB

railway_trip

#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define ep insert
#define endl '\n'
#define elif else if
#define pow pwr
#define sqrt sqrtt
#define int long long
#define ll long long
typedef unsigned long long ull;
using namespace std;
const int N=2e5+5;
int a[N],n,q,k,dis[N];
vector<int> adj[N];
void bfs(int s){
    for (int i=1;i<=n;i++) dis[i]=-1;
    dis[s]=0;
    queue<int> q;
    q.push(s);
    while (!q.empty()){
        int x=q.front();
        q.pop();
        for (auto u:adj[x]){
            if (dis[u]==-1){
                dis[u]=dis[x]+1;
                q.push(u);
            }
        }
    }return;
}
int32_t main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    cin>>n>>k>>q;
    for (int i=1;i<=n;i++) cin>>a[i];
    stack<int> s;
    for (int i=1;i<=n;i++){
        while (!s.empty() && a[i]>a[s.top()]) s.pop();
        if (!s.empty()) adj[i].pb(s.top()),adj[s.top()].pb(i);
        s.push(i);
    }
    while (!s.empty()) s.pop();
    for (int i=n;i>0;i--){
        while (!s.empty() && a[i]>a[s.top()]) s.pop();
        if (!s.empty()) adj[i].pb(s.top()),adj[s.top()].pb(i);
        s.push(i);
    }
    while (q--){
        int x,y;
        cin>>x>>y;
        bfs(x);
        cout<<dis[y]-1<<endl;
    }
    return 0;
}

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