My Java DFS solution


  • 0
    S
    public class Solution {
    public int numIslands(char[][] grid) {
        int res = 0;
        if (grid == null) return res;
        
        for (int i = 0; i<grid.length; i++){
            for (int j = 0; j<grid[0].length; j++){
                if (grid[i][j] == '1') {
                    res++;
                    dfs(grid, i, j);
                }
             }
        }
        return res;
       }
    
    private void dfs (char[][] grid, int i, int j){
        if (i < 0 || j < 0 || i >= grid.length || j >= grid[0].length || grid[i][j] != '1')
        return;
        
        grid[i][j] = '2';
        dfs (grid, i+1, j);
        dfs (grid, i-1, j);
        dfs (grid, i, j-1);
        dfs (grid, i, j+1);
        }
    

    }


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