Submission #1187366

#	Time	Username	Problem	Language	Result	Execution time	Memory
1187366		Aviansh	Rainforest Jumps (APIO21_jumps)	C++20	48 / 100	513 ms	63308 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];


struct segTree{
    int *st;
    int n;
    vector<int>ar;
    void rupdate(int l, int r, int ind, int i){
        if(i<l||i>r){
            return;
        }
        if(l==r){
            st[ind]=i;
            return;
        }
        int mid = (l+r)/2;
        rupdate(l,mid,ind*2+1,i);
        rupdate(mid+1,r,ind*2+2,i);
        if(ar[st[ind*2+1]]>ar[st[2*ind+2]]){
            st[ind]=st[ind*2+1];
        }
        else{
            st[ind]=st[ind*2+2];
        }
    }
    segTree(int siz, int arr[]){
        int x = ceil(log2(siz));
        x++;
        st=new int[(1<<x)];
        fill(st,st+(1<<x),0);
        n=siz-1;
        for(int i = 0;i<siz;i++){
            ar.push_back(arr[i]);
        }
        for(int i = 0;i<siz;i++){
            rupdate(0,n,0,i);
        }
    }
    int rquery(int l, int r, int s, int e, int ind){
        if(e<l||s>r){
            return -1;
        }
        if(s<=l&&r<=e){
            return st[ind];
        }
        int mid = (l+r)/2;
        int lef = rquery(l,mid,s,e,ind*2+1);
        int rig = rquery(mid+1,r,s,e,ind*2+2);
        if(lef==-1){
            return rig;
        }
        if(rig==-1){
            return lef;
        }
        if(ar[lef]>ar[rig]){
            return lef;
        }
        else{
            return rig;
        }
    }
    int query(int l, int r){
        return rquery(0,n,l,r,0);
    }
};

segTree st(maxn,h);

void init(int N, vector<int> H) {
    n=N;
    for(int i = 0;i<n;i++){
        h[i]--;
        h[i]=H[i];
        rev[h[i]-1]=i;
    }
    st=segTree(n,h);
    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);
    int leftmost = -1;
    if(g[c].size()){
        int cu = *min_element(g[c].begin(),g[c].end());
        if(cu<c)
            leftmost=cu;
    }
    leftmost++;
    a=max(a,leftmost);
    d=c;
    if(a>b)
        return -1;
    a=st.query(a,b);
    //assuming a=b,c=d
    //a will traverse rn
    for(int i = lg-1;i>=0;i--){
        if(h[opt[a][i]]<h[c]){
            ans+=(1<<i);
            a=opt[a][i];
        }
    }
    if(a!=opt[a][0]){
        if(h[opt[a][0]]<=h[c]){
            ans++;
            a=opt[a][0];
        }
    }
    //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]){
            ans+=(1<<i);
            a=nopt[a][i];
        }
    }
    if(a!=nopt[a][0]){
        if(h[nopt[a][0]]<=h[c]){
            ans++;
            a=nopt[a][0];
        }
    }
    if(a!=c){
        return -1;
    }
    //assert(ans!=0);
    assert(ans<n);
    return ans;
}

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