Submission #470104

#	Time	Username	Problem	Language	Result	Execution time	Memory
470104		Haruto810198	A Difficult(y) Choice (BOI21_books)	C++17	0 / 100	1 ms	200 KiB

books

#include <bits/stdc++.h>

#include "books.h"

#define ll long long
#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define vi vector<int>
#define pb push_back

using namespace std;
//
// --- 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 MAX = 100010;

ll arr[MAX];
ll sum[11]; // sum[i] : pref = i, suf = k - i
vector<int> res;

int query(int id){
    if(arr[id] == 0){
        arr[id] = skim(id);
    }
    return arr[id];
}

void solve(int N, int K, ll A, int Q){

    FOR(i, 1, K, 1){
        query(i);
        query(N-i+1);
    }

    FOR(i, 0, K, 1){ // sum[i]
        FOR(j, 1, i, 1){
            sum[i] += query(j);
        }
        for(int j = N; j > N - (K - i); j--){
            sum[i] += query(j);
        }
    }

    if(sum[0] < A or sum[K] > 2*A){
        impossible();
        return;
    }

    FOR(i, 0, K, 1){
        if(A <= sum[i] and sum[i] <= 2*A){
            FOR(j, 1, i, 1){
                res.pb(j);
            }
            for(int j = N; j > N - (K - i); j--){
                res.pb(j);
            }
            answer(res);
            return;
        }
    }

    int sum_id;
    int L, R, mid;

    for(int i = K; i >= 0; i--){
        if(sum[i] < A){
            sum_id = i;
            L = sum_id;
            R = L + (N - K);
        }
    }

    while(L < R){
        mid = (L + R) / 2;
        query(mid);
        int new_sum = sum[sum_id] - arr[sum_id] + arr[mid];
        if(new_sum >= A){
            R = mid;
        }
        else{
            L = mid + 1;
        }
    }

    FOR(j, 1, sum_id - 1, 1){
        res.pb(j);
    }
    for(int j = N; j > N - (K - sum_id); j--){
        res.pb(j);
    }

    res.pb(L);

    answer(res);
    return;

}

Compilation message (stderr)

books.cpp: In function 'void solve(int, int, long long int, int)':
books.cpp:80:18: warning: 'R' may be used uninitialized in this function [-Wmaybe-uninitialized]
   80 |         mid = (L + R) / 2;
      |               ~~~^~~~
books.cpp:6:41: warning: 'sum_id' may be used uninitialized in this function [-Wmaybe-uninitialized]
    6 | #define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
      |                                         ^~
books.cpp:68:9: note: 'sum_id' was declared here
   68 |     int sum_id;
      |         ^~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20