Submission #959477

#	Time	Username	Problem	Language	Result	Execution time	Memory
959477		Kavelmydex	Railway Trip (JOI17_railway_trip)	C++17	20 / 100	2037 ms	13444 KiB

railway_trip

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int,int>
#define vi vector<int>
#define rep(i,x,n) for(int i=x; i<n; ++i)
#define For(i,n) rep(i,0,n)
#define endl "\n"
#define sp ' '
#define pb push_back
#define f first
#define s second
#define sz size()
#define all(x) (x).begin(),(x).end()
 
const int N = 1e5+10, OO = 1e18, mod = 1e9+7, mx = 10;
void tr(int a, int b){cout << a << sp << b << endl;}
void cmx(int &a, int b){a = max(a,b);}
void cmn(int &a, int b){a = min(a,b);}
const int dx[]{0,0,-1,1}, dy[]{1,-1,0,0};

int a[N], L[N], R[N];
vi adj[N];
int32_t main() {
    ios::sync_with_stdio(0); cin.tie(0);
    // freopen("talent.in", "r", stdin);
    // freopen("talent.out", "w", stdout);
    int n,k,q; cin >> n >> k >> q;
    rep(i,1,n+1){
        cin >> a[i];
    }   
    vi lst,rst;
    rep(i,1,n+1){
        if(i==1) lst.pb(i), L[1]=-1;
        else {
            while(lst.sz && a[lst.back()] < a[i]) lst.pop_back();
            L[i] = lst.sz ? lst.back() : -1;
            lst.pb(i);
        }
    }
    for(int i=n; i>=1; --i){
        if(i==n) rst.pb(i), R[n]=-1;
        else {
            while(rst.sz && a[rst.back()] < a[i]) rst.pop_back();
            R[i] = rst.sz ? rst.back() : -1;
            rst.pb(i);
        }   
    }
    rep(i,1,n+1){
        if(L[i] != -1) adj[i].pb(L[i]), adj[L[i]].pb(i);
        if(R[i] != -1) adj[i].pb(R[i]), adj[R[i]].pb(i);
    }
    while(q--){
        int x,y; cin >> x >> y;
        queue <int> Q;
        Q.push(x);
        vi d(n+1,OO); d[x] = 0;
        while(Q.sz){
            int c = Q.front(); Q.pop();
            for(int i: adj[c]){
                if(d[c]+1 < d[i]){
                    d[i] = d[c]+1;
                    Q.push(i);
                }
            }
        }
        cout << d[y]-1 << endl;
    }
    return 0;
}
/*
Just some notices : 
I believe you can do it !
You've done things that were harder ... 
Stay calm and focused  =)
*/

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