Submission #1085299

#	Time	Username	Problem	Language	Result	Execution time	Memory
1085299		veehj	Railway Trip (JOI17_railway_trip)	C++17	100 / 100	419 ms	55896 KiB

railway_trip

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define F first
#define S second
#define pb push_back
#define sz(a) (ll)a.size()
#define all(x) (x).begin(), (x).end()

int main() {
    ll n, k, q; cin >> n >> k >> q;
    vector<ll> lvl(n); for(auto& u : lvl) cin >> u;
    vector<vector<vector<ll>>> stp(2, vector<vector<ll>>(n, vector<ll>(18, 0LL))); //v[left/right][place][2^?]=first point place will reach
    stack<ll> st;
    for(ll i=0; i<n; i++){
        while(!st.empty() && lvl[st.top()]<lvl[i]) st.pop();
        if(st.empty()) stp[0][i][0]=i;
        else stp[0][i][0]=st.top();
        st.push(i);
    }
    while(!st.empty()) st.pop();
    for(ll i=n-1; i>=0; i--){
        while(!st.empty() && lvl[st.top()]<lvl[i]) st.pop();
        if(st.empty()) stp[1][i][0]=i;
        else stp[1][i][0]=st.top();
        st.push(i);
    }
    for(int i=1; i<=17; i++){
        for(ll j=0; j<n; j++){
            stp[0][j][i]=min(stp[0][stp[0][j][i-1]][i-1], stp[0][stp[1][j][i-1]][i-1]);
            stp[1][j][i]=max(stp[1][stp[0][j][i-1]][i-1], stp[1][stp[1][j][i-1]][i-1]);
        }
    }
    while(q--){
        ll ans=0;
        //find the 2 sticked range
        ll a, b, l, r; cin >> a >> b;
        a--; b--;
        if(a>b) swap(a, b);
        l=r=a;
        for(int i=17; i>=0; i--){
            ll u=min(stp[0][l][i], stp[0][r][i]), v=max(stp[1][l][i], stp[1][r][i]);
            if(v<b){
                l=u, r=v;
                ans+=pow(2, i);
            }
        }
        a=r;
        l=r=b;
        for(int i=17; i>=0; i--){
            ll u=min(stp[0][l][i], stp[0][r][i]), v=max(stp[1][l][i], stp[1][r][i]);
            if(a<u){
                l=u, r=v;
                ans+=pow(2, i);
            }
        }
        //no need +1
        cout << ans << endl;
    }
}

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