Submission #489098

#	Time	Username	Problem	Language	Result	Execution time	Memory
489098		Theo830	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	2 ms	456 KiB

jumps

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ii,ll>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///APIO 2021 vc
//#include "jumps.h"
vector<vector<ll> >adj;
ll L[200005],R[200005];
ll l[200005][20],r[200005][20];
ll maxi[200005][20];
vector<int>arr;
ll n;
void init(int N, std::vector<int> H){
    n = N;
    arr = H;
    priority_queue<ii>pq;
    f(i,0,N){
        L[i] = R[i] = INF;
    }
    f(i,0,N){
        while(!pq.empty() && -pq.top().F < H[i]){
            R[pq.top().S] = i;
            pq.pop();
        }
        pq.push(ii(-H[i],i));
    }
    while(!pq.empty()){
        pq.pop();
    }
    for(ll i = N-1;i >= 0;i--){
        while(!pq.empty() && -pq.top().F < H[i]){
            L[pq.top().S] = i;
            pq.pop();
        }
        pq.push(ii(-H[i],i));
    }
    adj.assign(N+5,vll());
    f(i,0,N){
        if(L[i] != INF){
            adj[i].pb(L[i]);
        }
        if(R[i] != INF){
            adj[i].pb(R[i]);
        }
    }
    f(i,0,N){
        l[i][0] = L[i];
        r[i][0] = R[i];
        if(max(L[i],R[i]) == INF){
            maxi[i][0] = INF;
        }
        else if(H[L[i]] > H[R[i]]){
            maxi[i][0] = L[i];
        }
        else{
            maxi[i][0] = R[i];
        }
    }
    f(j,1,20){
        f(i,0,N){
            if(l[i][j-1] == INF){
                l[i][j] = INF;
            }
            else{
                l[i][j] = l[l[i][j-1]][j-1];
            }
            if(r[i][j-1] == INF){
                r[i][j] = INF;
            }
            else{
                r[i][j] = r[r[i][j-1]][j-1];
            }
            ll v = maxi[i][j-1];
            if(v == INF || maxi[v][j-1] == INF){
                maxi[i][j] = INF;
            }
            else{
                maxi[i][j] = maxi[v][j-1];
            }
        }
    }
}
int minimum_jumps(int A, int B, int C, int D) {
    ll s = B;
    for(ll j = 19;j >= 0;j--){
        if(A <= l[s][j]  && arr[l[s][j]] < arr[C]){
            s = l[s][j];
        }
    }
    ///C = D
    ll ans = 0;
    for(ll j = 19;j >= 0;j--){
        if(maxi[s][j] != INF && arr[maxi[s][j]] <= arr[C]){
            s = maxi[s][j];
            ans += (1LL<<j);
        }
    }
    assert(s != INF);
    if(L[s] != INF && arr[L[s]] <= arr[C]){
        for(ll j = 19;j >= 0;j--){
            if(l[s][j] != INF && arr[l[s][j]] <= arr[C]){
                ans += (1LL<<j);
                s = l[s][j];
            }
        }
    }
    if(R[s] != INF && arr[R[s]] <= arr[C]){
        for(ll j = 19;j >= 0;j--){
            if(r[s][j] != INF && arr[r[s][j]] <= arr[C]){
                ans += (1LL<<j);
                s = r[s][j];
            }
        }
    }
    if(s != C){
        ans = -1;
    }
    return ans;
}

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• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
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• Subtask 7: 0 / 19