diff --git a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/README.md b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/README.md
new file mode 100644
index 000000000..663c673aa
--- /dev/null
+++ b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/README.md
@@ -0,0 +1,46 @@
+# [1001.Grid Illumination][title]
+
+## Description
+Given the `root` of a binary tree, replace the value of each node in the tree with the **sum of all its cousins' values**.
+
+Two nodes of a binary tree are **cousins** if they have the same depth with different parents.
+
+Return the `root` of the modified tree.
+
+**Note** that the depth of a node is the number of edges in the path from the root node to it.
+
+**Example 1:**  
+
+![1](./example11.png)
+
+```
+Input: root = [5,4,9,1,10,null,7]
+Output: [0,0,0,7,7,null,11]
+Explanation: The diagram above shows the initial binary tree and the binary tree after changing the value of each node.
+- Node with value 5 does not have any cousins so its sum is 0.
+- Node with value 4 does not have any cousins so its sum is 0.
+- Node with value 9 does not have any cousins so its sum is 0.
+- Node with value 1 has a cousin with value 7 so its sum is 7.
+- Node with value 10 has a cousin with value 7 so its sum is 7.
+- Node with value 7 has cousins with values 1 and 10 so its sum is 11.
+```
+
+**Example 2:**  
+
+![2](./diagram33.png)
+
+```
+Input: root = [3,1,2]
+Output: [0,0,0]
+Explanation: The diagram above shows the initial binary tree and the binary tree after changing the value of each node.
+- Node with value 3 does not have any cousins so its sum is 0.
+- Node with value 1 does not have any cousins so its sum is 0.
+- Node with value 2 does not have any cousins so its sum is 0.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/cousins-in-binary-tree-ii
+[me]: https://github.com/kylesliu/awesome-golang-algorithm
diff --git a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution.go b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution.go
index d115ccf5e..cd9daa9d0 100755
--- a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution.go
+++ b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution.go
@@ -1,5 +1,37 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type TreeNode struct {
+	Val         int
+	Left, Right *TreeNode
+}
+
+func Solution(root *TreeNode) *TreeNode {
+	if root == nil {
+		return nil
+	}
+	sum := 0
+	queue := [][2]*TreeNode{{nil, root}}
+	root.Val = 0
+	for len(queue) > 0 {
+		nq := make([][2]*TreeNode, 0)
+		sum = 0
+		del := make(map[*TreeNode]int)
+		for _, item := range queue {
+			if item[1].Left != nil {
+				nq = append(nq, [2]*TreeNode{item[1], item[1].Left})
+				sum += item[1].Left.Val
+				del[item[1]] += item[1].Left.Val
+			}
+			if item[1].Right != nil {
+				nq = append(nq, [2]*TreeNode{item[1], item[1].Right})
+				sum += item[1].Right.Val
+				del[item[1]] += item[1].Right.Val
+			}
+		}
+		for _, item := range nq {
+			item[1].Val = sum - del[item[0]]
+		}
+		queue = nq
+	}
+	return root
 }
diff --git a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution_test.go b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution_test.go
index 14ff50eb4..f014dc8ae 100755
--- a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution_test.go
+++ b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/Solution_test.go
@@ -10,12 +10,41 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *TreeNode
+		expect *TreeNode
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &TreeNode{
+			Val: 5,
+			Left: &TreeNode{
+				Val:   4,
+				Left:  &TreeNode{Val: 1},
+				Right: &TreeNode{Val: 10},
+			},
+			Right: &TreeNode{
+				Val:   9,
+				Right: &TreeNode{Val: 7},
+			},
+		}, &TreeNode{
+			Val: 0,
+			Left: &TreeNode{
+				Val:   0,
+				Left:  &TreeNode{Val: 7},
+				Right: &TreeNode{Val: 7},
+			},
+			Right: &TreeNode{
+				Val:   0,
+				Right: &TreeNode{Val: 11},
+			},
+		}},
+		{"TestCase1", &TreeNode{
+			Val:   3,
+			Left:  &TreeNode{Val: 1},
+			Right: &TreeNode{Val: 2},
+		}, &TreeNode{
+			Val:   0,
+			Left:  &TreeNode{Val: 0},
+			Right: &TreeNode{Val: 0},
+		}},
 	}
 
 	//	开始测试
@@ -30,10 +59,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }
diff --git a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/diagram33.png b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/diagram33.png
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diff --git a/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/example11.png b/leetcode/2601-2700/2641.Cousins-in-Binary-Tree-II/example11.png
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