Submission #495156

#	Time	Username	Problem	Language	Result	Execution time	Memory
495156		mansur	Chessboard (IZhO18_chessboard)	C++14	70 / 100	513 ms	780 KiB

chessboard

#include<bits/stdc++.h>	
 
/*
#pragma optimize ("g",on)
#pragma GCC optimize("inline")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC optimize ("03")
#pragma GCC target ("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
*/

//01001101 01100001 01101011 01101000 01100001  01100111 01100001 01111001 

using namespace std;

#define all(a) a.begin(), a.end()                                                   
#define rall(a) a.rbegin(), a.rend()
#define ll long long
#define pb push_back
#define sz(a) a.size()
#define nl '\n'
#define popb pop_back()                                                                   
#define ld double
#define ull unsigned long long
#define ff first                                         
#define ss second  
#define fix fixed << setprecision
#define pii pair<int, int>                          
#define E exit (0)
#define int long long
 
const int inf = 1e18, N = 2e5 + 1, mod = 998244353;                    

vector<pii> dir = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

int n, k;

int cnt0[N], cnt1[N];

void f(int x, int y, int val) {
	x = (x + val - 1) / val;
	y = (y + val - 1) / val;
	if (x % 2 == y % 2) cnt0[val]++;
	else cnt1[val]++;
}

bool prime(int n) {
	for (int i = 2; i <= sqrt(n); i++) if (n % i == 0) return 0;
	return 1;
}

main() {                                                         
	//freopen("cowrect.in", "r", stdin);                                                                                     
	//freopen("cowrect.out", "w", stdout);                                                                                     
	ios_base::sync_with_stdio(NULL);                                                                                        
	cin.tie(NULL);
	cin >> n >> k;
	if (prime(n)) {
		int cnt0 = 0, cnt1 = 0;
		for (int i = 1; i <= k; i++) {
			int x1, y1, x2, y2;
			cin >> x1 >> y1 >> x2 >> y2;
			if (x1 % 2 == y1 % 2) {
				cnt0++;
			}else {
				cnt1++;
	        }
		}
		cout << min(cnt0 + n * n / 2 - cnt1, cnt1 + n * n / 2 + 1 - cnt0);
		return 0;
	}
	for (int i = 1; i <= k; i++) {
		int x1, y1, x2, y2;
		cin >> x1 >> y1 >> x2 >> y2;
		for (int val = 1; val <= sqrt(n); val++) {
			if (n % val == 0) {
				f(x1, y1, val);
				if (n / val != val)
					f(x1, y1, n / val);
			}	
		}
	}
	int mn = inf;
	for (int i = 1; i < n; i++) {
		if (n % i) continue;
		mn = min(mn, min(cnt0[i] + (n / i * (n / i)) / 2 * i * i - cnt1[i], cnt1[i] + (n / i * (n / i) + 1) / 2 * i * i - cnt0[i]));
	}
	cout << mn;
}                                 

Compilation message (stderr)

chessboard.cpp:52:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   52 | main() {
      | ^~~~

• Subtask 1: 8 / 8
• Subtask 2: 8 / 8
• Subtask 3: 15 / 15
• Subtask 4: 16 / 16
• Subtask 5: 23 / 23
• Subtask 6: 0 / 30