FB面经 Prepare: Count Unique Island

数unique island, 比如

110000

110001

001101

101100

100000

总共两个unique岛，不是四个

方法可以是记录每次新的岛屿搜索的路径，left,right,up,down, 作为标志是否相同的key，存hashset

 package fbOnsite;
 import java.util.*;
 public class UniqueIsland {
     public int countIsland(int[][] grid) {
         HashSet<String> set = new HashSet<String>();

         for (int i=0; i<grid.length; i++) {
             for (int j=0; j<grid[0].length; j++) {
                 if (grid[i][j] != 1) continue;
                 StringBuilder path = new StringBuilder();
                 dfs(grid, i, j, path.append('s')); //start
                 set.add(path.toString());
             }
         }

         for(String str : set) {
             System.out.println(str);
         }

         return set.size();
     }

     public void dfs(int[][] grid, int i, int j, StringBuilder sb) {
         grid[i][j] = 2;
         //up
         if (i>=1 && grid[i-1][j]==1) dfs(grid, i-1, j, sb.append('u'));
         //right
         if (j<grid[0].length-1 && grid[i][j+1]==1) dfs(grid, i, j+1, sb.append('r'));
         //down
         if (i<grid.length-1 && grid[i+1][j]==1) dfs(grid, i+1, j, sb.append('d'));
         //left
         if (j>=1 && grid[i][j-1]==1) dfs(grid, i, j-1, sb.append('l'));
     }

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         UniqueIsland sol = new UniqueIsland();
         int[][] grid = new int[][]{{1,1,0,0,0,0},{1,1,0,0,0,1},{0,0,1,1,0,0},{1,0,1,1,0,0,},{1,0,0,0,0,0}};
         int res = sol.countIsland(grid);
         System.out.println(res);
     }

 }