Submission #1022675

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022675		JakobZorz	Radio Towers (IOI22_towers)	C++17	23 / 100	4094 ms	3032 KiB

towers

#include"towers.h"
#include<vector>
#include<iostream>
using namespace std;

int n;
vector<int>arr;
vector<int>thres;
vector<int>prv,nxt;

void init_prev(){
    prv.resize(n);
    vector<int>s;
    for(int i=0;i<n;i++){
        while(s.size()&&arr[s.back()]>arr[i])
            s.pop_back();
        if(s.empty())
            prv[i]=-1;
        else
            prv[i]=s.back();
        s.push_back(i);
    }
}

void init_nxt(){
    nxt.resize(n);
    vector<int>s;
    for(int i=n-1;i>=0;i--){
        while(s.size()&&arr[s.back()]>arr[i])
            s.pop_back();
        if(s.empty())
            nxt[i]=-1;
        else
            nxt[i]=s.back();
        s.push_back(i);
    }
}

void init_thres(){
    thres.resize(n);
    for(int i=0;i<n;i++){
        int mn=2e9;
        
        if(prv[i]!=-1){
            int mx1=0;
            for(int j=i;j>prv[i];j--)
                mx1=max(mx1,arr[j]);
            mn=min(mn,mx1);
        }
        
        if(nxt[i]!=-1){
            int mx2=0;
            for(int j=i;j<nxt[i];j++)
                mx2=max(mx2,arr[j]);
            mn=min(mn,mx2);
        }
        
        thres[i]=mn-arr[i];
    }
}

void init(int N,vector<int>H){
    arr=H;
    n=(int)arr.size();
    init_prev();
    init_nxt();
    init_thres();
}

int max_towers(int L,int R,int D){
    int first=-1,last=-1;
    int res=0;
    for(int i=L;i<=R;i++){
        if(thres[i]>=D){
            res++;
            if(first==-1)
                first=i;
            last=i;
        }
    }
    if(first==-1){
        int sm=L;
        for(int i=L;i<=R;i++)
            if(arr[i]<arr[sm])
                sm=i;
        
        int mx=0;
        for(int i=sm;i<=R;i++){
            if(arr[i]<=mx-D)
                return 2;
            mx=max(mx,arr[i]);
        }
        
        mx=0;
        for(int i=sm;i>=L;i--){
            if(arr[i]<=mx-D)
                return 2;
            mx=max(mx,arr[i]);
        }
            
        return 1;
    }
    
    int mx=0;
    for(int i=first;i>=L;i--){
        if(max(arr[i],arr[first])+D<=mx){
            res++;
            break;
        }
        mx=max(mx,arr[i]);
    }
    
    mx=0;
    for(int i=last;i<=R;i++){
        if(max(arr[i],arr[last])+D<=mx){
            res++;
            break;
        }
        mx=max(mx,arr[i]);
    }
    
    return res;
}

• Subtask 1: 0 / 4
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23