Submission #1263119

#	Time	Username	Problem	Language	Result	Execution time	Memory
1263119		Aviansh	Obstacles for a Llama (IOI25_obstacles)	C++20	83 / 100	830 ms	71828 KiB

obstacles

#include <bits/stdc++.h>

using namespace std;

//min segTree

struct segTree{
    int *st;
    int n;
    segTree(int siz){
        int x = ceil(log2(siz));
        x++;
        n=siz-1;
        st = new int[(1<<x)];
        fill(st,st+(1<<x),0);
    }
    void rupdate(int l, int r, int ind, int i, int val){
        if(i<l||i>r){
            return;
        }
        if(l==r){
            st[ind]=val;
            return;
        }
        int mid = (l+r)/2;
        rupdate(l,mid,ind*2+1,i,val);
        rupdate(mid+1,r,ind*2+2,i,val);
        st[ind]=min(st[ind*2+1],st[ind*2+2]);
    }
    void update(int i, int val){
        rupdate(0,n,0,i,val);
    }

    int rquery(int l, int r, int s, int e, int ind){
        if(e<l||s>r){
            return 1e9;
        }
        if(s<=l&&r<=e){
            return st[ind];
        }
        int mid = (l+r)/2;
        return min(rquery(l,mid,s,e,ind*2+1),rquery(mid+1,r,s,e,ind*2+2));
    }

    int query(int l, int r){
        return rquery(0,n,l,r,0);
    }

};

map<array<int,2>,vector<array<int,2>>>g;

map<array<int,2>,array<int,2>>tp;

set<array<int,2>>rs;

array<int,2> dfs(array<int,2>st){
    if(g[st].size()==0){
        tp[st]=st;
        return st;
    }
    if(tp.find(st)!=tp.end()){
        return tp[st];
    }
    assert(g[st].size()==1);
    tp[st]=dfs(g[st][0]);
    return tp[st];
}

void initialize(vector<int> T, vector<int> H) {
    int n = T.size();
    int m = H.size();
    segTree st(m);
    set<array<int,2>>elems;
    for(int i = 0;i<m;i++) {
        st.update(i,H[i]);
        elems.insert({H[i],i});
    }
    segTree stt(n);
    for(int i = 0;i<n;i++){
        stt.update(i,T[i]);
    }
    //current ranges
    set<array<int,2>>rangs;
    int las = -1;
    for(int i = 0;i<m;i++){
        if(T[0]<=H[i]){
            //bad
            if(las!=-1){
                rs.insert({las,i-1});
            }
            las=-1;
        }
        else{
            if(las==-1)
                las=i;
        }
    }
    if(las!=-1){
        rs.insert({las,m-1});
    }
    //graph between ranges
    //stores when the range was first found
    map<array<int,2>,int>mp;

    auto it = elems.begin();
    for(int i = 0;i<n;i++){
        while(it!=elems.end()&&(*it)[0]<T[i]){
            int ind = (*it)[1];
            array<int,2>rang = {ind,ind};
            bool wor = 0;
            array<int,2>up = {-1,-1};
            auto itup = rangs.lower_bound(rang);
            if(itup != rangs.end()){
                //check if reachable, if yes then nice
                up = *itup;
                if(up[0]==ind+1){
                    rang[1]=up[1];
                    if(stt.query(mp[up],i)>st.query(up[0],up[1])){
                        wor=1;
                    }
                    rangs.erase(up);
                }
            }
            rangs.insert(rang);
            auto itdow = rangs.lower_bound(rang);
            if(itdow != rangs.begin()){
                itdow--;
                array<int,2>dow = *itdow;
                rangs.erase(rang);
                if(dow[1]==ind-1){
                    rang[0]=dow[0];
                    if(stt.query(mp[dow],i)>st.query(dow[0],dow[1])){
                        g[dow].push_back(rang);
                    }
                    rangs.erase(dow);
                }
                rangs.insert(rang);
            }
            if(wor){
                g[up].push_back(rang);
            }
            it++;
        }
    }
    for(array<int,2>a:rs){
        dfs(a);
    }
}

bool can_reach(int L, int R, int S, int D) {
    if(S>D){
        swap(S,D);
    }
    array<int,2> rangs = *(--rs.upper_bound({S,1000000000}));
    array<int,2> rangd = *(--rs.upper_bound({D,1000000000}));
    rangs=tp[rangs];
    rangd=tp[rangd];
    if(rangs==rangd){
        return 1;
    }
    return 0;
}

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 14 / 14
• Subtask 3: 13 / 13
• Subtask 4: 21 / 21
• Subtask 5: 25 / 25
• Subtask 6: 0 / 17