Submission #366928

#	Time	Username	Problem	Language	Result	Execution time	Memory
366928		wind_reaper	Carnival Tickets (IOI20_tickets)	C++17	16 / 100	666 ms	51692 KiB

tickets

#include "tickets.h"
#include <bits/stdc++.h>

using namespace std;

long long find_maximum(int k, vector<vector<int>> x) {
	int n = x.size(); 
	int m = x[0].size();
 
	vector<vector<int>> ans(n, vector<int>(m, -1));
 
	long long a = 0; 
 
	for(int i = 0; i < n; i++){
		for(int j = m-1; j >= m-k; --j){
			ans[i][j] = (m-1-j);
			a += 1LL*x[i][j];
		}
	}
 
	vector<array<int64_t, 4>> b;
 
	for(int i = 0; i < n; i++){
		for(int j = 1; j <= k; j++)
			b.push_back({x[i][k-j] + x[i][m-j], i, k-j, m-j});
	}
 
	sort(b.begin(), b.end());
	int e = 0;
	for(auto& [red, row, mn, mx] : b){
		if(e == (n*k)/2){
			break;
		}
		if(mn == mx){
			e++;
			continue;
		}
		if(ans[row][mx] == -1 || ans[row][mn] != -1)
			continue;
 		a -= 1LL*red;
		swap(ans[row][mx], ans[row][mn]);
		e++;
	}
 
	allocate_tickets(ans);
	return a;
}
/*
for every i, j < k exchange the i th minimum and j th maximum 
each exchange costs x[i] + x[j] ... take the first nk/2 valid exchanges
 
the actual order of the stuff doesnt matter
you wanna choose nk/2 pairs to remove
 
what happens when the stuff starts to overlap

...|..|...
..|.|..
*/

• Subtask 1: 0 / 11
• Subtask 2: 16 / 16
• Subtask 3: 0 / 14
• Subtask 4: 0 / 14
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23
• Subtask 7: 0 / 10