Method dfs

RegionsCutBySlashes.java:6–15

(int row, int col, int matrix[][])

    int dir[][] = {{-1,0},{0,1},{1,0},{0,-1}};
  //visit all nodes of a component using DFS
    public void dfs(int row, int col, int matrix[][]){
        //out of bound, already visited, obstacle
        if(row<0 || row>=rows || col<0 || col>=cols || matrix[row][col]==1){
            return;
        }
        matrix[row][col] = 1;
        for(int i=0;i<4;i++){
            dfs(row + dir[i][0], col + dir[i][1], matrix);
        }
    }
    public int regionsBySlashes(String[] grid) {
        //create a 3*3 grid
        int size = grid.length;