#include <iostream>
int main(){     //[k]天 [i]x [j]y
    int n,m,sum=0;char a[105][105][105]; std::cin>>n;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            std::cin>>a[1][i][j];
    std::cin>>m;
    for(int k=1;k<=m;k++){
        for(int i=1;i<=n;i++){
            for(int j=1;j<=n;j++){
                if(a[k-1][i][j]=='#')a[k][i][j]='#';
                else if(a[k-1][i][j]=='@'||
                        a[k-1][i-1][j]=='@'||
                        a[k-1][i][j-1]=='@'||
                        a[k-1][i+1][j]=='@'||
                        a[k-1][i][j+1]=='@')
                        a[k][i][j]='@';}}}
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            sum+=a[m][i][j]=='@'?1:0;
    std::cout<<sum; return 0;}

#include<iostream>
int n,m;
char g[101][101][101];
int main()
{
    std::cin>>n;
    for(int i=1;i<=n;i+=1)for(int j=1;j<=n;j+=1)std::cin>>g[1][i][j];
    std::cin>>m;
    for(int day=2;day<=m;day+=1)for(int i=1;i<=n;i+=1)for(int j=1;j<=n;j+=1)if(g[day-1][i][j]=='#')g[day][i][j]='#';else if(g[day-1][i-1][j]=='@'||g[day-1][i][j-1]=='@'||g[day-1][i][j]=='@'||g[day-1][i][j+1]=='@'||g[day-1][i+1][j]=='@')g[day][i][j]='@';
    int cnt=0;
    for(int i=1;i<=n;i+=1)for(int j=1;j<=n;j+=1)if(g[m][i][j]=='@')cnt+=1;
    std::cout<<cnt<<"\n";
}

很暴力

#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n, m, ans = 0;
    char a[105][105];
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            cin >> a[i][j];
    cin >> m;
    m--;
    while(m--)
    {
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
            {
                if (a[i][j] == '@' && a[i + 1][j] == '.')
                    a[i + 1][j] = '!';
                if (a[i][j] == '@' && a[i - 1][j] == '.')
                    a[i - 1][j] = '!';
                if (a[i][j] == '@' && a[i][j + 1] == '.')
                    a[i][j + 1] = '!';
                if (a[i][j] == '@' && a[i][j - 1] == '.')
                    a[i][j - 1] = '!';
            }
        }
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
                if (a[i][j] == '!')
                    a[i][j] = '@';
        }
        /*
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
                cout << a[i][j];
            cout << endl;
        }
        cout << endl;
        */
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= n; j++)
            if (a[i][j] == '@')
                ans++;
    }
    cout << ans << endl;
    return 0;
}