Add solution and test-cases for problem 3101

Author: 0xff-dev

leetcode/3101-3200/3101.Count-Alternating-Subarrays/README.md

@@ -1,28 +1,36 @@
 # [3101.Count Alternating Subarrays][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
+You are given a binary array `nums`.
+
+We call a subarray **alternating** if **no** two **adjacent** elements in the subarray have the **same** value.
+
+Return the number of alternating subarrays in `nums`.
+
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Input: nums = [0,1,1,1]
 
-## 题意
-> ...
+Output: 5
 
-## 题解
+Explanation:
 
-### 思路1
-> ...
-Count Alternating Subarrays
-```go
+The following subarrays are alternating: [0], [1], [1], [1], and [0,1].
 ```
 
+**Example 2:**
+
+```
+Input: nums = [1,0,1,0]
+
+Output: 10
+
+Explanation:
+
+Every subarray of the array is alternating. There are 10 possible subarrays that we can choose.
+```
 
 ## 结语
 

leetcode/3101-3200/3101.Count-Alternating-Subarrays/Solution.go

@@ -1,5 +1,25 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(nums []int) int64 {
+	l, cnt := len(nums), 0
+	ret := int64(l)
+	start, end := 0, 1
+
+	for ; end < l; end++ {
+		if nums[end] != nums[end-1] {
+			continue
+		}
+
+		length := end - start
+		cnt = (length - 1) * length / 2
+		ret += int64(cnt)
+
+		start = end
+	}
+
+	length := end - start
+	cnt = (length - 1) * length / 2
+	ret += int64(cnt)
+
+	return ret
 }

leetcode/3101-3200/3101.Count-Alternating-Subarrays/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 []int
+		expect int64
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{0, 1, 1, 1}, 5},
+		{"TestCase2", []int{1, 0, 1, 0}, 10},
 	}
 
 	//	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() {
 }