Submission #1296136

#TimeUsernameProblemLanguageResultExecution timeMemory
1296136aren_danceObstacles for a Llama (IOI25_obstacles)C++17
37 / 100
1343 ms35676 KiB
#include <bits/stdc++.h>
using namespace std;
struct segment
{
    int ar[2];
};

const int N=2e5+1;
const int inf=1e9;
int mast[N];
int mash[N];
int n,m;
int pref_maxv[N];
int pref_min[N];
int ri[N];
int le[N];
int ind[N];
int am[N];
segment seg[4*N];
int up[N][21];
segment merge(segment a,segment b){
    segment c;
    if(b.ar[1]>=a.ar[1]){
        c.ar[0]=a.ar[0];
    }
    else{
        c.ar[0]=b.ar[0];
    }
    c.ar[1]=min(a.ar[1],b.ar[1]);
    return c;
}

void update(int v,int s,int e,int pos,int new_val){
    if(s==e){
        seg[v]={pos,new_val};
        return;
    }
    int m=(s+e)/2;
    if(pos<=m){
        update(2*v,s,m,pos,new_val);
    }
    else{
        update(2*v+1,m+1,e,pos,new_val);
    }
    seg[v]=merge(seg[2*v],seg[2*v+1]);
}

segment get(int v,int s,int e,int l,int r){
    if(l>r){
        return {-1,inf};
    }
    if(l==s && e==r){
        return seg[v];
    }
    int mid=(s+e)/2;
    return merge(get(2*v,s,mid,l,min(r,mid)),get(2*v+1,mid+1,e,max(mid+1,l),r));
}

int query(int s,int e){
    int l=31-__builtin_clz(e-s+1);
    return max(up[s][l],up[e-(1<<l)+1][l]);
}

void initialize(vector<int> t, vector<int> h) {
    n=t.size();
    m=h.size();
    pref_min[0]=1e9;
    for(int i=1;i<4*N;++i){
        seg[i]={-1,inf};
    }
    for(int i=1;i<=n;++i){
        mast[i]=t[i-1];
        pref_maxv[i]=pref_maxv[i-1];
        if(mast[pref_maxv[i]]<mast[i]){
            pref_maxv[i]=i;
        }
        pref_min[i]=min(pref_min[i-1],mast[i]);
    }
    for(int i=1;i<=m;++i){
        mash[i]=h[i-1];
        up[i][0]=mash[i];
        update(1,1,m,i,mash[i]);
        int l=1;
        int r=n; 
        while(l<=r){
            int mid=(l+r)/2;
            if(pref_min[mid]>mash[i]){
                am[i]=pref_maxv[mid];
                l=mid+1;
            }
            else{
                r=mid-1;
            }
        }
    }
    for(int j=1;j<20;++j){    
        for(int i=1;i<=m;++i){
            up[i][j]=max(up[i][j-1],up[min(N-1,i+(1<<(j-1)))][j-1]);
        }
    }
    for(int i=m;i>0;--i){
        int l=i+1;
        int r=m;
        ri[i]=i;
        while(l<=r){
            int mid=(l+r)/2;
            if(query(i,mid)<mast[am[i]]){
                l=mid+1;
                ri[i]=ri[get(1,1,m,i,mid).ar[0]];
            }
            else{
                r=mid-1;
            }
        }
    }
    for(int i=1;i<=m;++i){
        int l=1;
        int r=i-1;
        le[i]=i;
        while(l<=r){
            int mid=(l+r)/2;
            if(query(mid,i)<mast[am[i]]){
                r=mid-1;
                le[i]=le[get(1,1,m,mid,i).ar[0]];
            } 
            else{
                l=mid+1;
            }
        }
    }
    for(int i=1;i<=m;++i){
        ind[i]=i;
    }
    for(int i=1;i<=m;++i){
        ind[i]=ind[ri[le[i]]];
    }
}

bool can_reach(int l, int r, int s, int d) {
    s++;
    d++;
    int mn=min(am[ind[s]],am[ind[d]]);
    int x=min(s,d);
    int y=max(s,d);
    if(query(x,y)<mast[mn]){
        return 1;
    }
    return 0;
}

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