y总代码注释版

#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> PII;

int change[4][4];

int get(int x, int y)
{
    return x * 4 + y;
}

int main()
{
    for (int i = 0; i < 4; i ++)
    {
        for (int j = 0; j < 4; j ++)
        {
            for (int k = 0; k < 4; k ++)
            {
                change[i][j] += (1 << get(i, k)) + (1 << get(k, j));
            }
            change[i][j] -= 1 << get(i, j);
        }
    }

    int state = 0;
    for (int i = 0; i < 4; i ++)
    {
        string line;
        cin >> line;

        for (int j = 0; j < 4; j ++)
        {
            if (line[j] == '+')
                state += 1 << get(i, j);
        }
    }

    vector <PII> path, temp;
    for (int i = 0; i < 1 <<16; i ++)
    {
        int now = state;
        temp.clear();

        for (int j = 0; j < 16; j ++)
        {
            if (i >> j & 1)
            {
                int x = i / 4, y = j % 4;
                now ^= change[i][j];
                temp.push_back({x, y});
            }
        }

        if (!now && (path.empty() || path.size() > temp.size())) path = temp;
    }

    cout << path.size() << endl;

    for (auto &e : path)
    {
        cout << e.first << ' ' << e.second << endl;
    }

    return 0;
}