Submission #949778

#TimeUsernameProblemLanguageResultExecution timeMemory
949778AiperiiiRainforest Jumps (APIO21_jumps)C++14
27 / 100
1148 ms42760 KiB
#include <bits/stdc++.h>
#include "jumps.h"
//#define int long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
const int N=2e5+5;
int jmp_high[N][20],jmp_low[N][20],t[N*4],ind[N*4];
vector <int> h;
int n;
void build(int v,int tl,int tr){
    if(tl==tr){
        t[v]=h[tl];
        ind[v]=tl;
    }
    else{
        int tm=(tl+tr)/2;
        build(v*2,tl,tm);
        build(v*2+1,tm+1,tr);
        if(t[v*2]<t[v*2+1]){
            t[v]=t[v*2+1];
            ind[v]=ind[v*2+1];
        }
        else{
            t[v]=t[v*2];
            ind[v]=ind[v*2];
        }
    }
}
pair <int,int> get(int v,int tl,int tr,int l,int r){
    if(r<tl or tr<l)return {-1e9,-1e9};
    if(l<=tl && tr<=r)return {t[v],ind[v]};
    pair <int,int> v1,v2;
    int tm=(tl+tr)/2;
    v1=get(v*2,tl,tm,l,r);
    v2=get(v*2+1,tm+1,tr,l,r);
    if(v1.ff<v2.ff)return v2;
    else return v1;
}
void init(int N,vector<int> H) {
    stack <int> st;
    n=N;
    for(int i=0;i<N;i++)h.pb(H[i]);
    h.pb(1e9);H.pb(1e9);
    vector <int> l(N+1,N),r(N+1,N);
    for(int i=0;i<N;i++){
        while(!st.empty() && H[st.top()]<H[i]){
            r[st.top()]=i;
            st.pop();
        }
        st.push(i);
    }
    while(!st.empty())st.pop();
    for(int i=N-1;i>=0;i--){
        while(!st.empty() && H[st.top()]<H[i]){
            l[st.top()]=i;
            st.pop();
        }
        st.push(i);
    }
    for(int i=0;i<=N;i++){
        if(H[l[i]]>H[r[i]]){
            jmp_high[i][0]=l[i];
            jmp_low[i][0]=r[i];
        }
        else{
            jmp_high[i][0]=r[i];
            jmp_low[i][0]=l[i];
        }
    }
    for(int k=1;k<20;k++){
        for(int i=0;i<=N;i++){
            jmp_high[i][k]=jmp_high[jmp_high[i][k-1]][k-1];
            jmp_low[i][k]=jmp_low[jmp_low[i][k-1]][k-1];
        }
    }
    build(1,0,N-1);
}

int minimum_jumps(int A, int B, int C, int D) {
    int l=A,r=B;
    int pos=A;
    while(l<=r){
        int md=(l+r)/2;
        pair <int,int> p=get(1,0,n-1,md,B);
        if(p.ff<=h[C])r=md-1;
        else{
            pos=md;
            l=md+1;
        }
    }
    A=get(1,0,n-1,pos,B).ss;
    int ans=0;
    for(int k=19;k>=0;k--){
        if(h[jmp_high[A][k]]<=h[C]){
            A=jmp_high[A][k];
            ans+=(1<<k);
        }
    }
    for(int k=19;k>=0;k--){
        if(h[jmp_low[A][k]]<=h[C]){
            A=jmp_low[A][k];
            ans+=(1<<k);
        }
    }
    if(A==C)return ans;
    return -1;
}
/*signed main(){
    ios_base::sync_with_stdio();
    cin.tie(0);cout.tie(0);
    int n,q;
    cin>>n>>q;
    vector <int> a(n);
    for(int i=0;i<n;i++)cin>>a[i];
    init(n,a);
    for(int i=0;i<q;i++){
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        cout<<minimum_jumps(a,b,c,d)<<"\n";
    }
}*/

/*
 
7 10
3 2 1 6 4 5 7
 
 */
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