#include <bits/stdc++.h>
#define mem(arr, num) memset(arr, num, sizeof arr)
#define F first
#define S second
#define INF 0x3f3f3f3f

using namespace std;

const int N = 10;
int sx, sy, ex, ey, n, m, t, ans;
int g[N][N], dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

void dfs(int x, int y)
{
    if (x == ex && y == ey)
    {
        ans ++;
        return;
    }

    for (int i = 0; i < 4; i ++ )
    {
        int xx = x + dx[i], yy = y + dy[i];
        if (xx > 0 && xx <= n && yy > 0 && yy <= m && !g[xx][yy])
        {
            g[xx][yy] = 1;
            dfs(xx, yy);
            g[xx][yy] = 0;
        }
    }

}

int main()
{
    cin.tie(0), cout.tie(0);

    cin >> n >> m >> t >> sx >> sy >> ex >> ey;

    while (t -- )
    {
        int a, b;
        cin >> a >> b;
        g[a][b] = 1;
    }
    dfs(sx, sy);

    cout << ans << endl;

    return 0;
}

最后才发现是没有对开始点初始化

#include <bits/stdc++.h>
#define mem(arr, num) memset(arr, num, sizeof arr)
#define F first
#define S second
#define INF 0x3f3f3f3f

using namespace std;

const int N = 10;
int sx, sy, ex, ey, n, m, t, ans;
int g[N][N], dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

void dfs(int x, int y)
{
    if (x == ex && y == ey)
    {
        ans ++;
        return;
    }

    for (int i = 0; i < 4; i ++ )
    {
        int xx = x + dx[i], yy = y + dy[i];
        if (xx > 0 && xx <= n && yy > 0 && yy <= m && !g[xx][yy])
        {
            g[xx][yy] = 1;
            dfs(xx, yy);
            g[xx][yy] = 0;
        }
    }

}

int main()
{
    cin.tie(0), cout.tie(0);

    cin >> n >> m >> t >> sx >> sy >> ex >> ey;
    g[sx][sy] = 1;

    while (t -- )
    {
        int a, b;
        cin >> a >> b;
        g[a][b] = 1;
    }
    dfs(sx, sy);

    cout << ans << endl;

    return 0;
}

这是过了的代码，记录与此，引以为戒；