Add solution and test-cases for problem 2807

leetcode/2801-2900/2807.Insert-Greatest-Common-Divisors-in-Linked-List/README.md

@@ -0,0 +1,42 @@
+# [2807.Insert Greatest Common Divisors in Linked List][title]
+
+## Description
+Given the `head` of a linked list head, in which each node contains an integer value.
+
+Between every pair of adjacent nodes, insert a new node with a value equal to the **greatest common divisor** of them.
+
+Return the linked list after insertion.
+
+The **greatest common divisor** of two numbers is the largest positive integer that evenly divides both numbers.
+
+**Example 1:**  
+
+![1](./ex1_copy.png)
+
+```
+Input: head = [18,6,10,3]
+Output: [18,6,6,2,10,1,3]
+Explanation: The 1st diagram denotes the initial linked list and the 2nd diagram denotes the linked list after inserting the new nodes (nodes in blue are the inserted nodes).
+- We insert the greatest common divisor of 18 and 6 = 6 between the 1st and the 2nd nodes.
+- We insert the greatest common divisor of 6 and 10 = 2 between the 2nd and the 3rd nodes.
+- We insert the greatest common divisor of 10 and 3 = 1 between the 3rd and the 4th nodes.
+There are no more adjacent nodes, so we return the linked list.
+```
+
+**Example 2:**  
+
+![2](./ex2_copy1.png)
+
+```
+Input: head = [7]
+Output: [7]
+Explanation: The 1st diagram denotes the initial linked list and the 2nd diagram denotes the linked list after inserting the new nodes.
+There are no pairs of adjacent nodes, so we return the initial linked list.
+```
+
+## 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/insert-greatest-common-divisors-in-linked-list
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2801-2900/2807.Insert-Greatest-Common-Divisors-in-Linked-List/Solution.go

@@ -1,5 +1,24 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func gcd2807(a, b int) int {
+	for b != 0 {
+		a, b = b, a%b
+	}
+	return a
+}
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func Solution(head *ListNode) *ListNode {
+	a, b := head, head.Next
+	for b != nil {
+		node := &ListNode{Val: gcd2807(a.Val, b.Val)}
+		a.Next = node
+		node.Next = b
+		a, b = b, b.Next
+	}
+	return head
 }

leetcode/2801-2900/2807.Insert-Greatest-Common-Divisors-in-Linked-List/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *ListNode
+		expect *ListNode
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &ListNode{Val: 18, Next: &ListNode{Val: 6, Next: &ListNode{Val: 10, Next: &ListNode{Val: 3}}}},
+			&ListNode{Val: 18, Next: &ListNode{Val: 6, Next: &ListNode{Val: 6, Next: &ListNode{Val: 2, Next: &ListNode{Val: 10, Next: &ListNode{Val: 1, Next: &ListNode{Val: 3}}}}}}}},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ 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() {
 }