Submission #379855

#	Time	Username	Problem	Language	Result	Execution time	Memory
379855		Kalashnikov	Chessboard (IZhO18_chessboard)	C++17	100 / 100	801 ms	5996 KiB

chessboard

#include <bits/stdc++.h>
 
#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)
#define all(a) a.begin() , a.end()
#define F first
#define S second
 
using namespace std;
using ll = long long;
#define y1 dsfsdf
#define int ll
const int N = 2e5+5 , inf = 2e9 + 7;
const ll INF = 1e18 ,   mod = 1e9+7 , P = 6547;

int x1[N] , y1[N] , x2[N] , y2[N];

void solve() {
	ll n, k;
	cin >> n >> k;
	if(k == 0) {
		ll ans = n*n / 2;
		for(int i = 2; i < n; i ++) {
			if(n%i == 0) {
				int x = i;
				if((n/x) % 2) {
					ans = min(ans , (n/x) * (n/x) / 2 * x*x);
				}
			}
		}
		cout << ans;
		return;
	}
	
	ll blacks = 0;
	for(int i = 1; i <= k; i ++) {
		cin >> x1[i] >> y1[i] >> x2[i] >> y2[i];
		blacks += (x2[i]-x1[i]+1) * (y2[i]-y1[i]+1);
		x1[i] --;
		x2[i] --;
		y1[i] --;
		y2[i] --;
	}
	
	
	ll ans = n*n;
	for(int i = 1; i < n; i ++) {
		if(n%i == 0) {
			int RightBlacks = 0;
			for(int j = 1; j <= k; j ++) {
				int cnt[2] , cnt1[2];
				fill(cnt , cnt+2 , 0);
				fill(cnt1 , cnt1+2 , 0);
				{
					int l = x1[j], r = x2[j];
					int l1 = l/i*i+i , r1 = r/i*i-1;
					if(l1 <= r1) {
						assert((r1-l1+1) % i == 0);
						int col = (r1-l1+1) / i;
						cnt[0] = col/2 * i;
						cnt[1] = col/2 * i;
						if(col%2) {
							cnt[l1/i % 2] += i;
						}
						cnt[l/i % 2] += l1-l;
						cnt[r/i % 2] += (r-r1);
					}
					else {
						int l1 = l , r1 = r , res;
						while(l1 <= r1) {
							int md = l1+r1 >> 1;
							if(l/i%2 == md/i%2) {
								res = md;
								l1 = md+1;
							}
							else {
								r1 = md-1;
							}
						}
						cnt[l/i%2] += res-l+1;
						cnt[r/i%2] += r-res;
					}
				}
				
				{
					int l = y1[j], r = y2[j];
					int l1 = l/i*i+i , r1 = r/i*i-1;
					if(l1 <= r1) {
						assert((r1-l1+1) % i == 0);
						int col = (r1-l1+1) / i;
						cnt1[0] = col/2 * i;
						cnt1[1] = col/2 * i;
						if(col%2) {
							cnt1[l1/i % 2] += i;
						}
						cnt1[l/i % 2] += l1-l;
						cnt1[r/i % 2] += (r-r1);
					}
					else {
						int l1 = l , r1 = r , res;
						while(l1 <= r1) {
							int md = l1+r1 >> 1;
							if(l/i%2 == md/i%2) {
								res = md;
								l1 = md+1;
							}
							else {
								r1 = md-1;
							}
						}
						cnt1[l/i%2] += res-l+1;
						cnt1[r/i%2] += r-res;
					}
				}
				RightBlacks += cnt[0] * cnt1[0];
				RightBlacks += cnt[1] * cnt1[1];
			}
			int a = (n/i)*(n/i) / 2 * i*i;
			int b = a;
			if((n/i) % 2) {
				a += i*i;
			}
			ans = min(ans , a-RightBlacks + (blacks - RightBlacks));
			ans = min(ans , b-(blacks - RightBlacks) + RightBlacks);
		}
	}
	cout << ans;
}
/*

*/
main() {
    ios;
    int tt = 1;
    //cin >> tt;
    while(tt --) {
        solve();
    }
    return 0;
}

Compilation message (stderr)

chessboard.cpp: In function 'void solve()':
chessboard.cpp:71:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   71 |        int md = l1+r1 >> 1;
      |                 ~~^~~
chessboard.cpp:102:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  102 |        int md = l1+r1 >> 1;
      |                 ~~^~~
chessboard.cpp: At global scope:
chessboard.cpp:132:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  132 | main() {
      |      ^
chessboard.cpp: In function 'void solve()':
chessboard.cpp:112:23: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
  112 |       cnt1[r/i%2] += r-res;
      |                      ~^~~~
chessboard.cpp:81:22: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
   81 |       cnt[r/i%2] += r-res;
      |                     ~^~~~

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