Submission #529196

#	Time	Username	Problem	Language	Result	Execution time	Memory
529196		Cross_Ratio	A Difficult(y) Choice (BOI21_books)	C++14	0 / 100	3 ms	1964 KiB

books

#include <bits/stdc++.h>
//#include "books.h"
using namespace std;
typedef long long ll;
ll D[100005];
ll skim(int);
void answer(vector<int>);
void impossible();
int cnt = 0;
ll get(int m) {
    if(D[m]!=-1) return D[m];
    assert(cnt<40);
    D[m] = skim(m+1);
    cnt++;
    return D[m];
}
void solve(int N, int K, ll A, int S) {
    int i, j, a, b;
    for(i=0;i<N;i++) D[i] = -1;
    ll sum = 0;
    for(i=0;i<K-1;i++) sum += get(i);
    if(sum >= A) {
        impossible();
        return;
    }
    int s = K-2, e = N-1;
    while(s+1<e) {
        int mid = (s + e + 1) >> 1;
        if(get(mid)>=A-sum) e = mid;
        else s = mid;
    }
    if(get(e)>=A-sum) {
        if(get(e)<=2*A-sum) {
            assert(0);
            vector<int> ans;
            for(i=1;i<=K-1;i++) ans.push_back(i);
            ans.push_back(e+1);
            answer(ans);
            return;
        }
        N = e;
    }
    if(N < K) {
        impossible();
        return;
    }
    for(i=0;i<=K;i++) {
        vector<int> ans;
        for(j=1;j<=i;j++) ans.push_back(j);
        for(j=N-K+1+i;j<=N;j++) ans.push_back(j);
        sort(ans.begin(),ans.end());
        ans.erase(unique(ans.begin(),ans.end()),ans.end());
        if(ans.size() != K) continue;
        ll sum = 0;
        for(int m=0;m<ans.size();m++) {
            sum += get(ans[m]-1);
        }
        if(sum >= A && sum <= 2*A) {
            answer(ans);
            return;
        }
    }
    impossible();
    return;
}

Compilation message (stderr)

books.cpp: In function 'void solve(int, int, ll, int)':
books.cpp:53:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   53 |         if(ans.size() != K) continue;
      |            ~~~~~~~~~~~^~~~
books.cpp:55:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |         for(int m=0;m<ans.size();m++) {
      |                     ~^~~~~~~~~~~
books.cpp:18:15: warning: unused variable 'a' [-Wunused-variable]
   18 |     int i, j, a, b;
      |               ^
books.cpp:18:18: warning: unused variable 'b' [-Wunused-variable]
   18 |     int i, j, a, b;
      |                  ^

• 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