Add solution and test-cases for problem 1375

leetcode/1301-1400/1375.Number-of-Times-Binary-String-Is-Prefix-Aligned/README.md

@@ -0,0 +1,42 @@
+# [1375.Number of Times Binary String Is Prefix-Aligned][title]
+
+## Description
+You have a **1-indexed** binary string of length `n` where all the bits are `0` initially. We will flip all the bits of this binary string (i.e., change them from `0` to `1`) one by one. You are given a **1-indexed** integer array `flips` where `flips[i]` indicates that the bit at index `i` will be flipped in the `ith` step.
+
+A binary string is **prefix-aligned** if, after the `ith` step, all the bits in the **inclusive** range `[1, i]` are ones and all the other bits are zeros.
+
+Return the number of times the binary string is **prefix-aligned** during the flipping process.
+
+**Example 1:**
+
+```
+Input: flips = [3,2,4,1,5]
+Output: 2
+Explanation: The binary string is initially "00000".
+After applying step 1: The string becomes "00100", which is not prefix-aligned.
+After applying step 2: The string becomes "01100", which is not prefix-aligned.
+After applying step 3: The string becomes "01110", which is not prefix-aligned.
+After applying step 4: The string becomes "11110", which is prefix-aligned.
+After applying step 5: The string becomes "11111", which is prefix-aligned.
+We can see that the string was prefix-aligned 2 times, so we return 2.
+```
+
+**Example 2:**
+
+```
+Input: flips = [4,1,2,3]
+Output: 1
+Explanation: The binary string is initially "0000".
+After applying step 1: The string becomes "0001", which is not prefix-aligned.
+After applying step 2: The string becomes "1001", which is not prefix-aligned.
+After applying step 3: The string becomes "1101", which is not prefix-aligned.
+After applying step 4: The string becomes "1111", which is prefix-aligned.
+We can see that the string was prefix-aligned 1 time, so we return 1.
+```
+
+## 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/number-of-times-binary-string-is-prefix-aligned
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/1301-1400/1375.Number-of-Times-Binary-String-Is-Prefix-Aligned/Solution.go

@@ -1,5 +1,14 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(flips []int) int {
+	ans := 0
+	sum, cur := 0, 0
+	for i, f := range flips {
+		sum += i + 1
+		cur += f
+		if sum == cur {
+			ans++
+		}
+	}
+	return ans
 }

leetcode/1301-1400/1375.Number-of-Times-Binary-String-Is-Prefix-Aligned/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 int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{3, 2, 4, 1, 5}, 2},
+		{"TestCase2", []int{4, 1, 2, 3}, 1},
 	}
 
 	//	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() {
 }