Add solution and test-cases for problem 541

leetcode/501-600/0541.Reverse-String-II/README.md

@@ -1,28 +1,23 @@
 # [541.Reverse String II][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 a string `s` and an integer `k`, reverse the first `k` characters for every `2k` characters counting from the start of the string.
+
+If there are fewer than `k` characters left, reverse all of them. If there are less than `2k` but greater than or equal to `k` characters, then reverse the first `k` characters and leave the other as original.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: s = "abcdefg", k = 2
+Output: "bacdfeg"
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Reverse String II
-```go
 ```
-
+Input: s = "abcd", k = 2
+Output: "bacd"
+```
 
 ## 结语
 

leetcode/501-600/0541.Reverse-String-II/Solution.go

@@ -1,5 +1,14 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(s string, k int) string {
+	bs := []byte(s)
+	start := 0
+	for start < len(s) {
+		nextStart := start + 2*k
+		for s, e := start, min(start+k-1, len(s)-1); s < e; s, e = s+1, e-1 {
+			bs[s], bs[e] = bs[e], bs[s]
+		}
+		start = nextStart
+	}
+	return string(bs)
 }

leetcode/501-600/0541.Reverse-String-II/Solution_test.go

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		str    string
+		k      int
+		expect string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", "abcdefg", 2, "bacdfeg"},
+		{"TestCase2", "abcd", 2, "bacd"},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.str, c.k)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",
+					c.expect, got, c.str, c.k)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }