Submission #1187298

#	Time	Username	Problem	Language	Result	Execution time	Memory
1187298		Aviansh	Rainforest Jumps (APIO21_jumps)	C++20	0 / 100	136 ms	47376 KiB

jumps

#include "jumps.h"

#include <bits/stdc++.h>

using namespace std;

const int maxn = 2e5+5;
const int lg = 22;
int h[maxn];
vector<int>g[maxn];
int rev[maxn];
int n;
int opt[maxn][lg];
int nopt[maxn][lg];

void init(int N, vector<int> H) {
    n=N;
    for(int i = 0;i<n;i++){
        h[i]=H[i];
        rev[h[i]-1]=i;
    }
    for(int i = 0;i<n;i++){
        fill(opt[i],opt[i]+lg,i);
        fill(nopt[i],nopt[i]+lg,i);
    }
    set<int>inds;
    for(int i = n-1;i>=0;i--){
        int ind = rev[i];
        if(inds.size()){
            auto it = inds.lower_bound(ind);
            int lef = -1;
            int rig = -1;
            if(it!=inds.end()){
                g[ind].push_back(*it);
                rig=*it;
            }
            if(it!=inds.begin()){
                it--;
                g[ind].push_back(*it);
                lef=*it;
            }
            if(lef==-1&&rig!=-1){
                //opt and nopt both go right
                opt[ind][0]=rig;
                nopt[ind][0]=rig;
                for(int i = 1;i<lg;i++){
                    opt[ind][i]=opt[opt[ind][i-1]][i-1];
                    nopt[ind][i]=nopt[nopt[ind][i-1]][i-1];
                }
            }
            if(lef!=-1&&rig==-1){
                //opt and nopt both go right
                opt[ind][0]=lef;
                nopt[ind][0]=lef;
                for(int i = 1;i<lg;i++){
                    opt[ind][i]=opt[opt[ind][i-1]][i-1];
                    nopt[ind][i]=nopt[nopt[ind][i-1]][i-1];
                }
            }
            if(lef!=-1&&rig!=-1){
                //now must see
                if(h[lef]<h[rig]){
                    swap(lef,rig);
                }
                //now lef is opt rig is nopt
                opt[ind][0]=lef;
                nopt[ind][0]=rig;
                for(int i = 1;i<lg;i++){
                    opt[ind][i]=opt[opt[ind][i-1]][i-1];
                    nopt[ind][i]=nopt[nopt[ind][i-1]][i-1];
                }
            }
        }
        inds.insert(rev[i]);
    }
    //graph creation done
    //kth ancestor shenanigans done
}

int minimum_jumps(int a, int b, int c, int d) {
    int ans = 0;
    //assert(a==b&&c==d);
    a=b;
    d=c;
    //assuming a=b,c=d
    //a will traverse rn
    for(int i = lg-1;i>=0;i--){
        if(h[opt[a][i]]>h[c]){
            continue;
        }
        else{
            if(i&&opt[a][i]==opt[a][i-1])
                continue;
            if(i==0&&opt[a][i]==a)
                continue;
            ans+=(1<<i);
            assert(a!=opt[a][i]);
            a=opt[a][i];
            //cout << "going to: " << a << " " << i << "\n";
        }
    }
    //cout << "opt done\n";
    //a is at best position, now nopts must occur
    for(int i = lg-1;i>=0;i--){
        if(h[nopt[a][i]]>h[c]){
            continue;
        }
        else{
            if(i&&nopt[a][i]==nopt[a][i-1])
                continue;
            if(i==0&&nopt[a][i]==a)
                continue;
            ans+=(1<<i);
            assert(a!=nopt[a][i]);
            a=nopt[a][i];
            //cout << "going to: " << a << " " << i << "\n";
        }
    }
    if(a!=c){
        return -1;
    }
    //assert(ans!=0);
    assert(ans<n);
    return ans;
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
• Subtask 5: 0 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19