Update 59. 岛屿数量.md

Author: jasoncao11

59. 岛屿数量.md

@@ -20,9 +20,13 @@ class Solution:
             if not 0<=i<len(grid) or not 0<=j<len(grid[0]) or grid[i][j] == '0':
                 return
             grid[i][j] = '0'
+            #情况1
             dfs(i+1,j)
+            #情况2
             dfs(i-1,j)
+            #情况3
             dfs(i,j+1)
+            #情况4
             dfs(i,j-1)
 
         for i in range(len(grid)):
@@ -33,4 +37,4 @@ class Solution:
                     count += 1
         #返回要优化的目标
         return count
-```
+```