day-23 岛屿的最大面积

思路：深度优先遍历，对每个是陆地且未曾访问过的位置进行dfs，统计每次进行dfs时的岛屿面积are，ans=Math.max(ans,are)

code:

class Solution {

    public int dir[][]={
   {
   0,1},{
   0,-1},{
   1,0},{
   -1,0}};
    public boolean vis[][];
    public int cows;
    public int cols;
    public int grid[][];
    public int ans=0;
    public int are=1;
    public int maxAreaOfIsland(int[][] grid) {

        cows=grid.length;
        if(cows==0)return 0;
        cols=grid[0].length;
        this.grid=grid;
        vis=new boolean[cows][cols];
        for(int i=0;i<cows;i++){

            for(int j=0;j<cols;j++){

                if(!vis[i][j]&&grid[i][j]==1){

                    dfs(i,j);
                    ans=Math.max(ans,are);
                    are=1;
                }
            }
        }
        return ans;
    }
    public void dfs(int i,int j){

        vis[i][j]=true;
        for(int k=0;k<4;k++){

            int newx=i+dir[k][0];
            int newy=j+dir[k][1];
            if(0<=newx&&newx<cows&&0<=newy&&newy<cols&&!vis[newx][newy]
            &&grid[newx][newy]==1){

                are=are+1;
                dfs(newx,newy);
            }
        }
    }
}

原文链接: https://blog.csdn.net/qq_53568730/article/details/136797597