【leetcode】com/problems/surrounded-regions/

dfs 栈溢出，bfs超时，用dfs非递归就不溢出了，前后写了1一个星期
class node
{
    int i;
    int j;
    
    public node(int i1,int j1)
    {
        i=i1;
        j=j1;
       
        
    }
}
    

public class Solution {
    public void solve(char[][] board) {
       
        int len1=board.length;
        if(len1<=0)return;
        int len2=board[0].length;
        if(len1<=2||len2<=2) return;
        for(int i=0;i<len1;i++)
        {
            if(board[i][0]=='O') dfs(board,i,0);
            if(board[i][len2-1]=='O') dfs(board,i,len2-1);
            
        }
        for(int i=0;i<len2;i++)
        {
            
            if(board[0][i]=='O')dfs(board,0,i);
            if(board[len1-1][i]=='O')dfs(board,len1-1,i);
        }
        for(int i=0;i<len1;i++)
        {
            for(int j=0;j<len2;j++)
            {
                if(board[i][j]=='h') board[i][j]='O';
                else  board[i][j]='X';
            }
        }
        
        
    }
    public boolean is(int i,int j,int len1,int len2)
    {
        if(i>=0&&i<len1&&j>=0&&j<len2) return true;
        return false;
        
        
    }
    public void dfs(char b[][],int i,int j)
    {
        int len1=b.length;
        int len2=b[0].length;
       Stack<node> s=new Stack<node>();
       b[i][j]='h';
       s.push(new node(i,j));
       
       
       
       
         
        
    }
}