Submission #173828

#	Time	Username	Problem	Language	Result	Execution time	Memory
173828		emil_physmath	Red-blue table (IZhO19_stones)	C++17	100 / 100	250 ms	2476 KiB

stones

#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
using namespace std;

void SwapMN(vector<string>& a)
{
    int n = a.size(), m = a[0].length();
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < m; ++j)
            a[i][j] = (a[i][j] == '-' ? '+' : '-');
    swap(n, m);
    vector<string> temp(n, string(m, '-'));
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < m; ++j)
            temp[i][j] = a[j][i];
    a.swap(temp);
}
int Value(const vector<string>& a)
{
    int n = a.size();
    int m = a[0].length();
    int res = 0;
    for (int i = 0; i < n; ++i)
        if (2 * count(a[i].begin(), a[i].end(), '+') > m)
            ++res;
    for (int j = 0; j < m; ++j)
    {
        int cnt = 0;
        for (int i = 0; i < n; ++i)
            if (a[i][j] == '-')
                ++cnt;
        if (2 * cnt > n)
            ++res;
    }
    return res;
}
bool Solve(int n, int nx, int m, int mx, bool swapMN)
{
    if (nx < 0 || mx < 0 || nx > n || mx > m) return false;
    if (swapMN)
    {
        swap(n, m);
        swap(nx, mx);
    }
    vector<string> a(n, string(m, '-'));
    for (int i = n - nx; i < n; ++i)
        for (int j = 0; j < m; ++j)
            a[i][j] = '-';
    for (int i = 0; i < n; ++i)
        for (int j = m - mx; j < m; ++j)
            a[i][j] = '+';
    int block = ((m + 2) / 2 - mx);
    int j = m - mx - 1;
    if (mx < m)
        for (int i = 0; i < n - nx; ++i)
        {
            for (int cnt = 0; cnt < block; ++cnt)
                a[i][(j - cnt + m - mx) % (m - mx)] = '+';
            j = (j - block + m - mx) % (m - mx);
        }
    if (swapMN)
    {
        swap(n, m);
        swap(nx, mx);
        SwapMN(a);
    }
    int value = Value(a);
    if (value < n + m - nx - mx)
        return false;
    cout << value << '\n';
    for (int i = 0; i < n; ++i)
        cout << a[i] << '\n';
    cout << flush;
    return true;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t;
    cin >> t;
    while (t--)
    {
        int n, m;
        cin >> n >> m;
        bool printed = false;
        for (int sum = 0; !printed && sum <= 4; ++sum)
            for (int i = 0; !printed && i <= 4; ++i)
                if (Solve(n, i, m, sum - i, false) || Solve(n, i, m, sum - i, true))
                {
                    printed = true;
                    break;
                }
    }
}

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