Submission #1009531

#	Time	Username	Problem	Language	Result	Execution time	Memory
1009531		bachhoangxuan	Radio Towers (IOI22_towers)	C++17	0 / 100	4038 ms	9684 KiB

towers

#include "towers.h"
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5+5;
const int maxl = 20;

int N,D=-1;
vector<int> H;
int nxt[maxn][maxl],lt[maxn],rt[maxn];

void build(int _D){
    vector<int> v;D=_D;
    for(int i=0;i<=N;i++) lt[i]=rt[i]=-1,nxt[i][0]=N;
    for(int i=0;i<N;i++){
        while(!v.empty() && H[v.back()]>H[i]) v.pop_back();
        int l=0,r=(int)v.size()-1;
        while(l<=r){
            int mid=(l+r)>>1;
            if(H[v[mid]]<=H[i]-D) lt[i]=v[mid],l=mid+1;
            else r=mid-1;
        }
        v.push_back(i);
    }
    v.clear();
    for(int i=N-1;i>=0;i--){
        while(!v.empty() && H[v.back()]>H[i]) v.pop_back();
        int l=0,r=(int)v.size()-1;
        while(l<=r){
            int mid=(l+r)>>1;
            if(H[v[mid]]<=H[i]-D) rt[i]=v[mid],l=mid+1;
            else r=mid-1;
        }
        v.push_back(i);
    }
    for(int i=0;i<N;i++){
        if(lt[i]==-1 || rt[i]==-1) continue;
        nxt[lt[i]][0]=min(nxt[lt[i]][0],rt[i]);
    }
    for(int i=0;i<N;i++) nxt[i][0]=min(nxt[i][0],nxt[i+1][0]);
    for(int i=1;i<18;i++) for(int j=0;j<=N;j++) nxt[j][i]=nxt[nxt[j][i-1]][i-1];
}

void init(int _N, std::vector<int> _H){
    N=_N;H=_H;
}

int max_towers(int L, int R, int _D){
    if(_D!=D) build(_D);
    int cnt=1;
    for(int i=17;i>=0;i--){
        if(nxt[L][i]<=R) L=nxt[L][i],cnt+=(1<<i);
    }
    return cnt;
}

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