solve: number of islands

Author: sounmind

number-of-islands/evan.py

@@ -0,0 +1,29 @@
+from typing import List
+
+
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
+        if not grid:
+            return 0
+
+        rows, cols = len(grid), len(grid[0])
+        count = 0
+
+        def dfs(r, c):
+            if r < 0 or c < 0 or r >= rows or c >= cols or grid[r][c] == "0":
+                return
+
+            grid[r][c] = "0"
+            
+            dfs(r + 1, c)
+            dfs(r - 1, c)
+            dfs(r, c + 1)
+            dfs(r, c - 1)
+
+        for row in range(rows):
+            for col in range(cols):
+                if grid[row][col] == "1":
+                    count += 1
+                    dfs(row, col)
+
+        return count