```c
#include <iostream>
using namespace std;
const int N = 110;
int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
int st[N];
char g[N][N];
int n, m, maxx = 0;
void bfs(int x, int y, int cnt)
{
maxx = max(maxx, cnt);
for(int i = 0; i < 4; i ++ )
{
int nx = x + dx[i], ny = y + dy[i];
if(nx >= 0 && nx < n && ny >= 0 && ny < m && st[g[nx][ny]] == 0)
{
st[g[nx][ny]] = 1;
bfs(nx, ny, cnt + 1);
st[g[nx][ny]] = 0;
}
}
}
int main()
{
cin >> n >> m;
for(int i = 0; i < n; i ++ )for(int j = 0; j < m; j ++ )cin >> g[i][j];
st[g[0][0]] = 1;
bfs(0, 0, 1);
cout << maxx << endl;
return 0;
}
```
by dzkccc @ 2024-04-27 14:41:47
why? ? ? @[dzkccc](/user/1277552)
by 123uuu @ 2024-05-04 12:23:21
发错了
by dzkccc @ 2024-05-04 14:42:10