leetcode: finished #427

content/leetcode/2024/2.md

@@ -3,6 +3,58 @@ title: 2024.2
 draft: false
 ---
 
+# 2024.2.19
+
+```python
+#
+# @lc app=leetcode.cn id=427 lang=python3
+#
+# [427] 建立四叉树
+#
+
+# @lc code=start
+"""
+# Definition for a QuadTree node.
+class Node:
+    def __init__(self, val, isLeaf, topLeft, topRight, bottomLeft, bottomRight):
+        self.val = val
+        self.isLeaf = isLeaf
+        self.topLeft = topLeft
+        self.topRight = topRight
+        self.bottomLeft = bottomLeft
+        self.bottomRight = bottomRight
+"""
+
+
+class Solution:
+    def construct(self, grid: List[List[int]]) -> "Node":
+        def is_leaf(x, y, length):
+            for i in range(x, x + length):
+                for j in range(y, y + length):
+                    if grid[i][j] != grid[x][y]:
+                        return False
+            return True
+
+        def construct_tree(x, y, length):
+            if is_leaf(x, y, length):
+                return Node(grid[x][y] == 1, True, None, None, None, None)
+            else:
+                half = length // 2
+                return Node(
+                    "*",
+                    False,
+                    construct_tree(x, y, half),
+                    construct_tree(x, y + half, half),
+                    construct_tree(x + half, y, half),
+                    construct_tree(x + half, y + half, half),
+                )
+
+        return construct_tree(0, 0, len(grid))
+
+
+# @lc code=end
+```
+
 # 2024.2.18
 
 ```python