Submission #1125416

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125416		zhasyn	Red-blue table (IZhO19_stones)	C++20	53 / 100	52 ms	2120 KiB

stones

#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
using namespace std;
#define F first
#define S second
typedef long long ll;
#define pii pair <int, int>
#define pll pair <ll, ll>
typedef long double ld;
const ll N = 1000 + 100, M = 500 + 10, len = 315, inf = 1e18;
const ll mod = 998244353;
ll um(ll a, ll b){
	return (1LL * a * b) % mod;
}
ll subr(ll a, ll b){
	return ((1LL * a - b) % mod + mod) % mod;
}
ll bp(ll x, ll step){
	ll res = 1;
	while(step){
		if(step & 1) res = um(res, x);
		x = um(x, x);
		step /= 2;
	}
	return res;
}
ll inv(ll x){
	return bp(x, mod - 2);
}
ll n, m, a, b;
char arr[N][N];
int check1(){
	for(int i = 0; i < n; i++){
		for(int j = 0; j < m; j++){
			arr[i][j] = '+';
		}
	}
	for(int i = 0; i < n - a; i++){
		for(int j = 0; j < m; j++){
			arr[i][j] = '-';
		}
	}
	int start = n - a;
	for(int j = 0; j < b; j++){
		//cout << n/2 + 1 - a << endl;
		for(int i = 0; i < (n/2 + 1) - (n - a); i++){
			//cout << start << " " << j << endl;
			arr[start][j] = '-';
			if(++start == n) start = n - a;
		}
	}
	int ans = 0;
	for(int i = 0; i < n; i++){
		int cnt = 0;
		for(int j = 0; j < m; j++){
			if(arr[i][j] == '+') cnt++;
		}
		if(cnt >= m/2 + 1) ans++;
	}
	for(int j = 0; j < m; j++){
		int cnt = 0;
		for(int i = 0; i < n; i++){
			if(arr[i][j] == '-') cnt++;
		}
		if(cnt >= n/2 + 1) ans++;
	}
	return ans;
}
void check2(){
	for(int i = 0; i < n; i++){
		for(int j = 0; j < m; j++){
			arr[i][j] = '-';
		}
	}
	for(int i = 0; i < n; i++){
		for(int j = 0; j < m - b; j++){
			arr[i][j] = '+';
		}
	}
	int start = m - b;
	for(int j = 0; j < a; j++){
		for(int i = 0; i < (m/2 + 1) - (m - b); i++){
			arr[j][start] = '+';
			if(++start == m) start = m - b;
		}
	}
}
int main() {
	//ios_base::sync_with_stdio(false);
	//cin.tie(nullptr);
	//cout.tie(nullptr);
	int tt;
	cin >> tt;
	while(tt--){
		cin >> n >> m;
		if(n >= 4 && m == 3){
			cout << n + 1 << endl;
			for(int i = 0; i < n; i++){
				cout << "++-\n";
			}
			continue;
		}
		int mx = 0;
		for(int i = 0; i <= n; i++){
			int cur = i + min((n * m - (m/2 + 1) * i) / (n/2 + 1), m);
			//cout << cur << " "<< i << " " << min((n * m - (m/2 + 1) * i) / (n/2 + 1), m) << endl;
			if(cur > mx){
				mx = cur;
				a = i;
				b = min((n * m - (m/2 + 1) * i) / (n/2 + 1), m);
			}
		}
		cout << mx << endl;
		//cout << a << " "<< b << endl;
		if(check1() != mx){
			check2();
		}
		
		for(int i = 0; i < n; i++){
			for(int j = 0; j < m; j++){
				cout << arr[i][j];
			}
			cout << endl;
		}
	}
  return 0;
}

• Subtask 1: 17 / 17
• Subtask 2: 10 / 10
• Subtask 3: 0 / 16
• Subtask 4: 11 / 11
• Subtask 5: 15 / 15
• Subtask 6: 0 / 31