diff --git a/LeetCodeSharp.Tests/P427Tests.cs b/LeetCodeSharp.Tests/P427Tests.cs
new file mode 100644
index 0000000..be8b06b
--- /dev/null
+++ b/LeetCodeSharp.Tests/P427Tests.cs
@@ -0,0 +1,17 @@
+namespace LeetCodeSharp.Tests;
+
+using LeetCodeSharp.Problems427;
+
+public class P427Tests
+{
+    [Fact]
+    public void Test1()
+    {
+        int[][] grid = [[0, 1], [1, 0]];
+
+        Solution solution = new();
+        Node root = solution.Construct(grid);
+
+        Assert.False(root.isLeaf);
+    }
+}
\ No newline at end of file
diff --git a/LeetCodeSharp/Problems/Solution427.cs b/LeetCodeSharp/Problems/Solution427.cs
new file mode 100644
index 0000000..8bfb91a
--- /dev/null
+++ b/LeetCodeSharp/Problems/Solution427.cs
@@ -0,0 +1,137 @@
+// [427] Construct Quad Tree
+
+
+namespace LeetCodeSharp.Problems427
+{
+    // Submission codes start here
+
+    /*
+// Definition for a QuadTree node.
+public class Node {
+    public bool val;
+    public bool isLeaf;
+    public Node topLeft;
+    public Node topRight;
+    public Node bottomLeft;
+    public Node bottomRight;
+
+    public Node() {
+        val = false;
+        isLeaf = false;
+        topLeft = null;
+        topRight = null;
+        bottomLeft = null;
+        bottomRight = null;
+    }
+
+    public Node(bool _val, bool _isLeaf) {
+        val = _val;
+        isLeaf = _isLeaf;
+        topLeft = null;
+        topRight = null;
+        bottomLeft = null;
+        bottomRight = null;
+    }
+
+    public Node(bool _val,bool _isLeaf,Node _topLeft,Node _topRight,Node _bottomLeft,Node _bottomRight) {
+        val = _val;
+        isLeaf = _isLeaf;
+        topLeft = _topLeft;
+        topRight = _topRight;
+        bottomLeft = _bottomLeft;
+        bottomRight = _bottomRight;
+    }
+}
+*/
+    public class Node
+    {
+        public bool val;
+        public bool isLeaf;
+        public Node topLeft;
+        public Node topRight;
+        public Node bottomLeft;
+        public Node bottomRight;
+
+        public Node()
+        {
+            val = false;
+            isLeaf = false;
+            topLeft = null;
+            topRight = null;
+            bottomLeft = null;
+            bottomRight = null;
+        }
+
+        public Node(bool _val, bool _isLeaf)
+        {
+            val = _val;
+            isLeaf = _isLeaf;
+            topLeft = null;
+            topRight = null;
+            bottomLeft = null;
+            bottomRight = null;
+        }
+
+        public Node(bool _val, bool _isLeaf, Node _topLeft, Node _topRight, Node _bottomLeft, Node _bottomRight)
+        {
+            val = _val;
+            isLeaf = _isLeaf;
+            topLeft = _topLeft;
+            topRight = _topRight;
+            bottomLeft = _bottomLeft;
+            bottomRight = _bottomRight;
+        }
+    }
+
+    public class Solution
+    {
+        public Node Construct(int[][] grid)
+        {
+            var length = grid.Length;
+
+            return ConstructRecursive(grid, 0, 0, length);
+        }
+
+        private Node ConstructRecursive(int[][] grid, int startX, int startY, int length)
+        {
+            if (IsSameGrid(grid, startX, startY, length))
+            {
+                return new Node(grid[startX][startY] == 1, true);
+            }
+
+            var middleX = startX + length / 2;
+            var middleY = startY + length / 2;
+            var middleLength = length / 2;
+
+            var root = new Node
+            {
+                topLeft = ConstructRecursive(grid, startX, startY, middleLength),
+                topRight = ConstructRecursive(grid, startX, middleY, middleLength),
+                bottomLeft = ConstructRecursive(grid, middleX, startY, middleLength),
+                bottomRight = ConstructRecursive(grid, middleX, middleY, middleLength)
+            };
+
+            return root;
+        }
+
+        private bool IsSameGrid(int[][] grid, int startX, int startY, int length)
+        {
+            var value = grid[startX][startY];
+
+            for (var i = 0; i < length; i++)
+            {
+                for (var j = 0; j < length; j++)
+                {
+                    if (grid[startX + i][startY + j] != value)
+                    {
+                        return false;
+                    }
+                }
+            }
+
+            return true;
+        }
+    }
+
+    // Submission codes end here
+}
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