pass 200 bfs medium

200-240525-pass/main.py

@@ -0,0 +1,58 @@
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
+        searched_cell = set()
+        def va(s):
+            return int(s)
+        # bfs
+        ans = 0
+        row = len(grid)
+        column = len(grid[0])
+        def add_node(que, idx, node):
+            if len(que) <= idx:
+                que.append(node)
+            else:
+                que[idx] = node
+        def is_valid_node(node):
+            i = node[0]
+            j = node[1]
+            return i >= 0 and j >= 0 and i < row and j <column
+        flag = []
+        for i, l in enumerate(grid):
+            flag.append([])
+            for j, lee in enumerate(l):
+                flag[i].append(0)
+        for i, l in enumerate(grid):
+            for j, ele in enumerate(l):
+                val = va(grid[i][j])
+                if val == 0 : continue
+                # if (i,j) in searched_cell: continue
+                if flag[i][j] == 1: continue
+                que = [(i, j)]
+                idx = 0
+                while idx >= 0:
+                    node = que[idx]
+                    # if node in searched_cell: continue
+                    idx -= 1
+                    if flag[node[0]][node[1]] == 1: continue
+                    flag[node[0]][node[1]] = 1
+                    if va(grid[node[0]][node[1]]) == 0: continue                    
+                    up = (node[0] - 1, node[1])
+                    down = (node[0] + 1, node[1])
+                    left = (node[0], node[1] - 1)
+                    right = (node[0], node[1] + 1)
+                    if is_valid_node(up):
+                        idx += 1
+                        add_node(que, idx, up)
+                    if is_valid_node(down):
+                        idx += 1
+                        add_node(que,idx, down)
+                    if is_valid_node(left):
+                        idx += 1
+                        add_node(que, idx, left)
+                    if is_valid_node(right):
+                        idx += 1
+                        add_node(que,idx, right)
+                ans += 1
+        return ans
+
+