Submission #901143

#	Time	Username	Problem	Language	Result	Execution time	Memory
901143		simona1230	A Difficult(y) Choice (BOI21_books)	C++17	100 / 100	1 ms	1112 KiB

books

#include <bits/stdc++.h>
#include "books.h"
using namespace std;

long long n,k,a,s;
long long x[120001];

long long val(int idx)
{
    if(x[idx]==0)x[idx]=skim(idx);
    return x[idx];
}

void solve(int N,int K,long long A,int S)
{
    n=N;
    k=K;
    a=A;
    s=S;

    int lidx=k,ridx=n,idx=0;
    while(lidx<=ridx)
    {
        int m=(lidx+ridx)/2;
        if(val(m)>=a)
        {
            idx=m;
            ridx=m-1;
        }
        else lidx=m+1;
    }

    if(idx>=k)
    {
        long long fk=0;
        for(int i=1; i<k; i++)
            fk+=val(i);

        if(fk+val(idx)>=a&&fk+val(idx)<=2*a)
        {
            vector<int> ans;
            for(int i=1; i<k; i++)
                ans.push_back(i);
            ans.push_back(idx);
            answer(ans);
            return;
        }
        if(idx==k)
        {
            impossible();
            return;
        }
    }

    if(idx==0)idx=n;
    else idx--;

    long long sum=0;
    for(int i=1;i<=k;i++)
        sum+=val(i);
    if(sum>=a&&sum<=2*a)
    {
        vector<int> ans;
        for(int i=1;i<=k;i++)
            ans.push_back(i);
        answer(ans);
        return;
    }

    int lf=1,rt=max(k+1,idx-k+1);

    while(lf<=k&&rt<=idx&&sum<a)
    {
        sum-=val(lf);lf++;
        sum+=val(rt);rt++;

        if(sum>=a&&sum<=2*a)
        {
            vector<int> ans;
            for(int i=lf;i<=k;i++)
                ans.push_back(i);
            for(int i=max(k+1,idx-k+1);i<rt;i++)
                ans.push_back(i);
            answer(ans);
            return;
        }
    }
    impossible();
}
/*
10 4 20 11
1 2 3 4 5 15 16 17 18 19

10 5 10 10
1 2 3 4 5 6 7 8 9 100
*/

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 20 / 20
• Subtask 7: 20 / 20