Submission #657991

#	Time	Username	Problem	Language	Result	Execution time	Memory
657991		Lobo	A Difficult(y) Choice (BOI21_books)	C++17	100 / 100	1 ms	336 KiB

books

#include <bits/stdc++.h>
#include "books.h"
using namespace std;
#define int long long
#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define all(x) x.begin(),x.end()

//
// --- Sample implementation for the task books ---
//
// To compile this program with the sample grader, place:
//     books.h books_sample.cpp sample_grader.cpp
// in a single folder and run:
//     g++ books_sample.cpp sample_grader.cpp
// in this folder.
//
const int maxn = 1e5+10;
const int maxv = 2e18+10;
int n, b[maxn];
int cnt;
int qry(int32_t i) {
    if(b[i] == 0) {
        assert(cnt--);
        return b[i] = skim(i);
    }
    return b[i];
}

int qrysum(int l, int r) {
    int sum = 0;
    for(int i = l; i <= r; i++) {
        sum+= qry(i);
        sum = min(sum,maxv);
    }
    return sum;
}
void solve(int32_t N, int32_t k, long long A, int32_t S) {
    cnt = 50;
    n = N;

    int l,r;

    l = 1;
    r = n;
    int p = -1;
    while(l <= r) {
        int mid = (l+r)/2;
        if(qry(mid) >= A) {
            r = mid-1;
            p = mid;
        }
        else {
            l = mid+1;
        }
    }

    if(p != -1) {
        if(p < k) {
            impossible();
            return;
        }
        if(qrysum(1,k-1)+qry(p) <= 2*A) {
            vector<int32_t> ans;
            for(int j = 1; j <= k-1; j++) ans.pb(j);
            ans.pb(p);
            answer(ans);
            return;
        }

        if(p == k) {
            impossible();
            return;
        }
        n = p-1;
        // n is >= k
    }

    // l = 1;
    // r = n-k+1;
    // while(l <= r) {
    //     int mid = (l+r)/2;
    //     if(qrysum(mid,mid+k-1) < A) {
    //         l = mid+1;
    //     }
    //     else if(qrysum(mid,mid+k-1) > 2*A) {
    //         r = mid-1;
    //     }
    //     else {
    //         vector<int32_t> ans;
    //         for(int j = mid; j <= mid+k-1; j++) ans.pb(j);
    //         answer(ans);
    //         return;
    //     }
    // }

    int sumcur = qrysum(1,k);
    if(sumcur > 2*A) {
        impossible();
        return;
    }
    if(sumcur >= A) {
        vector<int32_t> ans;
        for(int j = 1; j <= k; j++) ans.pb(j);
        answer(ans);
        return;
    }

    vector<int32_t> ans;
    for(int i = k; i >= 1; i--) {
        if(sumcur-qry(i)+qry(n) < A) {
            sumcur = sumcur-qry(i)+qry(n);
            ans.pb(n);
            n--;
        }
        else if(sumcur-qry(i)+qry(n) <= 2*A) {
            //I found the answer
            ans.pb(n);
            for(int j = 1; j < i; j++) ans.pb(j);
            sort(all(ans));
            answer(ans);
            return;
        }
        else {
            l = i;
            r = n;

            while(l <= r) {
                int mid = (l+r)/2;
                if(sumcur-qry(i)+qry(mid) > 2*A) {
                    r = mid-1;
                }
                else if(sumcur-qry(i)+qry(mid) < A) {
                    l = mid+1;
                }
                else {
                    ans.pb(mid);
                    for(int j = 1; j < i; j++) ans.pb(j);
                    sort(all(ans));
                    answer(ans);
                    return;
                }
            }
        }
    }

    impossible();
}

• 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