Submission #495051

#	Time	Username	Problem	Language	Result	Execution time	Memory
495051		mansur	Chessboard (IZhO18_chessboard)	C++14	8 / 100	26 ms	716 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 = 1e9, N = 2e5 + 1, mod = 998244353;                    

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

int c[1001][1001];

int n, k;

int get(int s, int p) {
	int cnt = p, ans = 0;
	for (int i = 1; i <= n; i += s) {
		for (int j = 1; j <= n; j += s) {
			if (i != 1) {
				if (c[i - 1][j]) cnt = 0;
				else cnt = 1;
			}
			if (j != 1) {
				if (c[i][j - 1]) cnt = 0;
				else cnt = 1;
			}
        	for (int x = i; x <= i + s - 1; x++) {
        		for (int y = j; y <= j + s - 1; y++) {
        			if (cnt && !c[x][y]) {
        				ans++;	
        				c[x][y] = 1;
        			}else if (!cnt && c[x][y]) {
        				ans++;
        				c[x][y] = 0;
        			}
        		}
        	}
        }
	}
	return ans;
}

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;
		c[x1][y1] = 1;
	}
	int mn = inf;
	for (int val = 1; val < n; val++) {
		if (n % val) continue;
		mn = min(mn, min(get(val, 0), get(val, 1)));		
	}
	cout << mn;
}                                 

Compilation message (stderr)

chessboard.cpp:73:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   73 | main() {
      | ^~~~

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