Submission #941571

#	Time	Username	Problem	Language	Result	Execution time	Memory
941571		shoryu386	A Difficult(y) Choice (BOI21_books)	C++17	0 / 100	1 ms	612 KiB

books

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

void solve(int N, int K, long long A, int S) {
    // TODO implement this function
    
    //k books, sum of A
    typedef long long ll;
    
    //x, x+1, x+2, x+3, x+4, x+5... and so on
    
    int extrasum = 0;
    for (int x = 0; x < K; x++){
		extrasum += x;
	}
	
	//we want A <= x*K + extrasum <= 2*A
	//x*K + extrasum >= A
	//x*K >= A-extrasum
	//x >= (A-extrasum)/K
	
	ll target = (A - extrasum)/K + ((A - extrasum)%K != 0);
	//to do: check rounding
	
	if (A - extrasum <= 0) {impossible(); return;}
	
	int l = 1, r = N+1-K, ans = N+1-K;
	while (l <= r){
		int m = (l+r)/2;
		
		ll res = skim(m);
		
		if (res >= target){
			r = m-1;
			ans = m;
		}
		else{
			l = m+1;
		}
	}
	
	
	ll sum = 0; deque<int> vals;
	
	for (int x = ans; x < ans + K; x++){
		int res = skim(x);
		sum += res; vals.push_back(res);
	}
	
	if (ans != N+1-K) assert(sum >= A);
	
	int lowest = ans;
	
	for (int x = 0; x < min(10, lowest-1); x++){
		if (sum <= 2LL*A){
			vector<int> res; for (int x = lowest; x < lowest+K; x++) res.push_back(x);
			
			answer(res);
		}
		else{
			sum -= vals.back();
			vals.pop_back();
			
			lowest--;
			int v = skim(lowest);
			vals.push_front(v);
			sum += v;
		}
	}
	if (sum <= 2LL*A){
		vector<int> res; for (int x = lowest; x < lowest+K; x++) res.push_back(x);
		
		answer(res);
	}
	impossible();
}

• 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