Number of Islands

 1     // Accepted
 2        public int numIslands(char[][] grid) {
 3              if ( grid == null || grid.length == 0 )
 4                  return 0;
 5             boolean visited[][] = new boolean[grid.length][grid[0].length];
 6             int count = 0;
 7             for(int i = 0 ; i < grid.length; i++ )
 8             {
 9                 for(int j = 0 ; j <grid[0].length; j++ )
10                 {
11                     if( grid[i][j] == ‘1‘ && visited[i][j] == false )
12                     {
13                         DFS(grid,i,j,visited);
14                         count++;
15                     }
16                 }
17             }
18 
19             return count;
20     
21         }
22         public  void DFS(char [][]grid, int i ,int j, boolean [][]visited){
23 
24                 if( visited[i][j] != false)
25                         return;
26                 int x = 0, y =0;
27                 visited[i][j] = true;
28                 //up
29                 x = i-1;
30                 y = j;
31                 if( x >= 0  && grid[x][y] == ‘1‘ && visited[x][y] == false ){
32                     DFS(grid, x, y ,visited);
33                 }
34                 
35                 //down
36                 x = i + 1;
37                 y = j;
38                 if( x < grid.length  && grid[x][y] == ‘1‘ && visited[x][y] == false ){
39                     DFS(grid, x, y ,visited);
40                 }
41 
42                 //left
43                 x = i;
44                 y = j-1;
45                 if( y >= 0 && grid[x][y] == ‘1‘ && visited[x][y] == false ){
46                     DFS(grid, x, y ,visited);
47                 }
48                 
49 
50                 //right
51                 x = i;
52                 y = j+1;
53                 if( y < grid[0].length  && grid[x][y] == ‘1‘ && visited[x][y] == false ){
54                     DFS(grid, x, y ,visited);
55                 }
56 
57         }