Submission #1026399

#	Time	Username	Problem	Language	Result	Execution time	Memory
1026399		Mardonbekhazratov	Radio Towers (IOI22_towers)	C++17	41 / 100	4059 ms	4960 KiB

towers

#include "towers.h"

#include <vector>
#include <algorithm>
#include <iostream>
#include <map>
#include <set>

using namespace std;

struct SegTree{
    int N;
    vector<int>tree;

    int merge(int a,int b){
        return max(a,b);
    }

    void build(int n){
        N=1;
        while(N<n) N<<=1;
        
        tree.assign(2*N,0);
    }

    void update(int v,int l,int r,int id,int x){
        if(r-l==1){
            tree[v]=x;
            return;
        }
        int mid=(l+r)/2;
        if(id<mid) update(v<<1,l,mid,id,x);
        else update(v<<1|1,mid,r,id,x);
        tree[v]=merge(tree[v<<1],tree[v<<1|1]);
    }

    void update(int id,int x){
        return update(1,0,N,id,x);
    }

    int get(int v,int l,int r,int ql,int qr){
        if(ql>=r || l>=qr) return 0;
        if(l>=ql && qr>=r) return tree[v];

        int mid=(l+r)/2;
        return merge(get(v<<1,l,mid,ql,qr),get(v<<1|1,mid,r,ql,qr));
    }

    int get(int l,int r){
        if(r<=l) return 0;
        return get(1,0,N,l,r);
    }
};

int n,k;
vector<int>h,pref;
bool su1=true;


void init(int N, std::vector<int> H) {
    n=N;
    h=H;
    k=0;
    bool ok=true;
    pref.resize(n);
    pref[0]=0;
    vector<int>last(n);
    for(int i=1;i<n;i++){
        if(h[i]>h[i-1] && ok) k=i;
        else{
            if(h[i]>h[i-1]) su1=false;
            ok=false;
        }
        pref[i]=pref[i-1];
        if(h[i]<h[i-1]){
            if(last[i-1]==1) pref[i]++;
            last[i]=-1;
        }
        else{
            last[i]=1;
        }
    }
}

int max_towers(int L, int R, int D) {
    if(su1){
        if(L<k && R>k && h[k]-D>=h[L] && h[k]-D>=h[R]) return 2;
        return 1;
    }
    if(D==1){
        return pref[R]-pref[min(R,L+1)]+1;
    }
    vector<int>a,dp(R-L+1);
    dp[0]=1;
    for(int i=L;i<=R;i++){
        a.push_back(h[i]);
    }
    
    // map<int,int>mp;
    vector<int>b=a;
    sort(b.begin(),b.end());
    int c=b.size();
    // for(int x:b) m[x]=c++;
    SegTree S1,S2;
    S1.build(c+2);
    S2.build(c+2);
    
    int ans=1,mx=0;
    for(int i=0;i<a.size();i++){
        int pos=lower_bound(b.begin(),b.end(),a[i]+D)-b.begin();
        dp[i]=S2.get(pos,c+2);
        dp[i]++;
        ans=max(ans,dp[i]);
        int pos2=lower_bound(b.begin(),b.end(),a[i])-b.begin();
        S1.update(pos2,dp[i]);
        int pos1=lower_bound(b.begin(),b.end(),a[i]-D+1)-b.begin();
        S2.update(pos2,S1.get(0,pos1));
        // cout<<dp[i]<<' ';
    }
    return ans;
}

Compilation message (stderr)

towers.cpp: In function 'int max_towers(int, int, int)':
towers.cpp:109:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  109 |     for(int i=0;i<a.size();i++){
      |                 ~^~~~~~~~~
towers.cpp:108:15: warning: unused variable 'mx' [-Wunused-variable]
  108 |     int ans=1,mx=0;
      |               ^~

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