Visul

#include <bits/stdc++.h>

using namespace std;

ifstream fin("vis.in");
ofstream fout("vis.out");

int n, c, nr, a[21][21], posibilitati;

bool corect(int i, int j)
{
    return i >= 1 && i <= n && j <= n && j >= 1;
}

void vis(int i, int j)
{
    if(i == n)
    {
        posibilitati++;
        return;
    }

    if(a[i+1][j] == 0 && corect(i+1, j))
    {
        vis(i+1, j);
    }

    if(a[i+1][j-1] == 1 && corect(i+1, j-1))
    {
        vis(i+1, j-1);
    }

    if(a[i+1][j+1] == 1 && corect(i+1, j+1))
    {
        vis(i+1, j+1);
    }
}

int main()
{
    fin >> n >> c >> nr;
    for(int i = 1; i <= nr; i++)
    {
        int x, y;
        fin >> x >> y;
        a[x][y] = 1;
    }
    vis(1, c);

    fout << posibilitati;

    fin.close();
    fout.close();
    return 0;
}