Merge pull request #371 from 0xff-dev/master

Add solution and test-cases for problem 1339

Author: Cori1109

leetcode/1301-1400/1339.Maximum-Product-of-Splitted-Binary-Tree/README.md

@@ -1,28 +1,29 @@
 # [1339.Maximum Product of Splitted Binary Tree][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+Given the `root` of a binary tree, split the binary tree into two subtrees by removing one edge such that the product of the sums of the subtrees is maximized.
+
+Return the maximum product of the sums of the two subtrees. Since the answer may be too large, return it **modulo** 10<sup>9</sup> + 7.
+
+**Note** that you need to maximize the answer before taking the mod and not after taking it.
 
-**Example 1:**
+**Example 1:**  
+![example1](./sample_1_1699.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: root = [1,2,3,4,5,6]
+Output: 110
+Explanation: Remove the red edge and get 2 binary trees with sum 11 and 10. Their product is 110 (11*10)
 ```
 
-## 题意
-> ...
+**Example 2:**  
+![example2](./sample_2_1699.png)
 
-## 题解
-
-### 思路1
-> ...
-Maximum Product of Splitted Binary Tree
-```go
 ```
-
+Input: root = [1,null,2,3,4,null,null,5,6]
+Output: 90
+Explanation: Remove the red edge and get 2 binary trees with sum 15 and 6.Their product is 90 (15*6)
+```
 
 ## 结语
 

leetcode/1301-1400/1339.Maximum-Product-of-Splitted-Binary-Tree/Solution.go

@@ -1,5 +1,44 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type TreeNode struct {
+	Val         int
+	Left, Right *TreeNode
+}
+
+const mod1339 = 1000000007
+
+func Solution(root *TreeNode) int {
+	sum := treeSum(root)
+	ans := -1
+	splitTree(root, sum, &ans)
+	return ans % mod1339
+}
+
+func treeSum(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+
+	left := treeSum(root.Left)
+	right := treeSum(root.Right)
+	root.Val += left + right
+	return root.Val
+}
+
+func splitTree(root *TreeNode, sum int, ans *int) {
+	if root == nil {
+		return
+	}
+	if root.Left != nil {
+		splitTree(root.Left, sum, ans)
+	}
+
+	if root.Right != nil {
+		splitTree(root.Right, sum, ans)
+	}
+	diff := sum - root.Val
+	s := diff * root.Val
+	if *ans == -1 || s > *ans {
+		*ans = s
+	}
 }

leetcode/1301-1400/1339.Maximum-Product-of-Splitted-Binary-Tree/Solution_test.go

@@ -10,12 +10,43 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *TreeNode
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &TreeNode{
+			Val: 1,
+			Left: &TreeNode{
+				Val: 2,
+				Left: &TreeNode{
+					Val: 4,
+				},
+				Right: &TreeNode{
+					Val: 5,
+				},
+			},
+			Right: &TreeNode{
+				Val:  3,
+				Left: &TreeNode{Val: 6},
+			},
+		}, 110},
+		{"TestCase2", &TreeNode{
+			Val: 1,
+			Right: &TreeNode{
+				Val: 2,
+				Left: &TreeNode{
+					Val: 3,
+				},
+				Right: &TreeNode{
+					Val: 4,
+					Left: &TreeNode{
+						Val: 5,
+					},
+					Right: &TreeNode{
+						Val: 6,
+					},
+				},
+			},
+		}, 90},
 	}
 
 	//	开始测试
@@ -30,10 +61,10 @@ 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() {
 }