number of island solution

Author: hyeri0903

number-of-islands/hyeri0903.py

@@ -0,0 +1,33 @@
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
+        '''
+        m = 세로(열), n = 가로(행)
+        solution: dfs
+        '''
+        m = len(grid)
+        n = len(grid[0])
+        visited = [ [0] * n for _ in range(m)]
+        count = 0
+
+        def dfs(i, j):
+            #범위 벗어나면 return
+            if i < 0 or i >= m or j < 0 or j >= n or grid[i][j] == "0":
+                return
+
+            if visited[i][j] == 1:
+                return
+
+            visited[i][j] = 1 #방문표시
+
+            dfs(i+1, j)
+            dfs(i-1, j)
+            dfs(i, j+1)
+            dfs(i, j-1)
+        
+        for i in range(m):
+            for j in range(n):
+                if grid[i][j] == "1" and visited[i][j] == 0:
+                    dfs(i,j)
+                    count += 1
+        return count
+