Submission #988225

#	Time	Username	Problem	Language	Result	Execution time	Memory
988225		GrindMachine	Railway Trip (JOI17_railway_trip)	C++17	20 / 100	2037 ms	11008 KiB

railway_trip

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<ll> adj[N];

void solve(int test_case)
{
    ll n,k,q; cin >> n >> k >> q;
    vector<ll> a(n+5);
    rep1(i,n) cin >> a[i];

    auto add_edge = [&](ll u, ll v){
        adj[u].pb(v), adj[v].pb(u);
    };

    {
        stack<ll> stk;
        rep1(i,n){
            while(!stk.empty() and a[i] >= a[stk.top()]){
                add_edge(i,stk.top());
                stk.pop();
            }
            stk.push(i);
        }
    }

    {
        stack<ll> stk;
        rev(i,n,1){
            while(!stk.empty() and a[i] >= a[stk.top()]){
                add_edge(i,stk.top());
                stk.pop();
            }
            stk.push(i);
        }
    }

    vector<bool> vis(n+5);

    while(q--){
        ll s,t; cin >> s >> t;
        queue<pll> q;
        fill(all(vis),0);
        q.push({0,s});
        vis[s] = 1;

        ll ans = -1;

        while(!q.empty()){
            auto [cost,u] = q.front();
            q.pop();

            if(u == t){
                ans = cost;
                break;
            }

            trav(v,adj[u]){
                if(vis[v]) conts;
                q.push({cost+1,v});
                vis[v] = 1;
            }
        }

        assert(ans != -1);
        ans--;
        cout << ans << endl;
    }
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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