Submission #495194

#	Time	Username	Problem	Language	Result	Execution time	Memory
495194		Ierus	Chessboard (IZhO18_chessboard)	C++17	47 / 100	96 ms	26640 KiB

chessboard

#include<bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
*/
using namespace std;
#pragma GCC optimize ("unroll-loops,Ofast,O3")
#pragma GCC target("avx,avx2,fma")
#define F first
#define S second
#define sz(x) (int)x.size()
#define pb push_back
#define int long long
#define eb emplace_back
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define NFS 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 ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
typedef long long ll;
const int E = 1e6+777;
const long long inf = 1e18+777;
const int N = 1e5+777;
const int MOD = 1e9+7;
vector<int> div(int x){
	vector<int> res = {1};
	for(int i = 2; i <= x / 2; ++i){
		if(x % i == 0){
			res.pb(i);
		}
	}
	return res;
}
struct block{
	int x1, y1, x2, y2;
	void read(){
		cin >> x1 >> y1 >> x2 >> y2;
	}
}a[N];
int n, k;
int get1(){
	int b[N][2]{};
	for(int i = 1; i <= k; ++i){
		++b[a[i].x1][a[i].y1&1];
	}
	int cnt1 = n * n / 2 + (n & 1);
	int cnt2 = n * n - cnt1;
	int sum1 = 0, sum2 = 0;
	for(int i = 1; i <= n; ++i){
		if(i & 1){
			sum1 += b[i][1];
			sum2 += b[i][0];
		}else{
			sum1 += b[i][0];
			sum2 += b[i][1];
		}
	}
	return min(cnt1 - sum1 + sum2, cnt2 - sum2 + sum1);
}
int pref[2111][2111], ar[2111][2111];
void precalc(){
	for(int l = 1; l <= k; ++l){
		ar[a[l].x1][a[l].y1] = 1;
	}
	pref[1][1] = ar[1][1];
    for(int i = 2; i <= n; i++) {
        pref[i][1] = pref[i-1][1] + ar[i][1];
    }
    for(int i = 2; i <= n; i++) {
        pref[1][i] = pref[1][i-1] + ar[1][i];
    }
    for (int i = 2; i <= n; i++) {
        for (int j = 2; j <= n; j++) {
            pref[i][j] = pref[i-1][j] + pref[i][j-1] - pref[i-1][j-1] + ar[i][j];
        }
    }
}
long long query(int x1, int y1, int x2, int y2) {
    return pref[x2][y2] - pref[x1 - 1][y2] - pref[x2][y1 - 1] + pref[x1 - 1][y1 - 1];
}
int get2(vector<int> &d, int res = LLONG_MAX){
	precalc();
	for(auto x : d){
		int sum1 = 0, sum2 = 0, cnt1 = 0, cnt2 = 0;
		bool ok = 1;
		for(int i = 1; i <= n; i += x){
			for(int j = 1; j <= n; j += x){
				int x1 = i, y1 = j, x2 = i + x - 1, y2 = j + x - 1;
				int cur = query(x1, y1, x2, y2);
				if(ok & 1){
					sum1 += cur;
					cnt1 += x * x;
				}else{
					sum2 += cur;
					cnt2 += x * x;
				}
				ok ^= 1;
			}
			if((n / x) % 2 == 0) ok ^= 1;
		}
	res = min({res, cnt1 - sum1 + sum2, cnt2 - sum2 + sum1});
	}
	return res;
}
main(){
	cin >> n >> k;
	for(int i = 1; i <= k; ++i){
		a[i].read();	
	}
	vector<int> d = div(n);
	if(sz(d) == 1){
		cout << get1() << '\n';	
	}else{
		cout << get2(d);
	}
};

Compilation message (stderr)

chessboard.cpp:106:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  106 | main(){
      | ^~~~

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