doc: add Gurubase and update Sponsor text

README.md

@@ -10,6 +10,7 @@
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
+[![Gurubase](https://img.shields.io/badge/Gurubase-Ask%20Lancet%20Guru-006BFF)](https://gurubase.io/g/lancet)
 
 </div>
 

README_zh-CN.md

@@ -10,6 +10,7 @@
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
+[![Gurubase](https://img.shields.io/badge/Gurubase-Ask%20Lancet%20Guru-006BFF)](https://gurubase.io/g/lancet)
 
 </div>
 

docs/api/packages/mathutil.md

@@ -33,7 +33,7 @@ import (
 -   [Percent](#Percent)
 -   [RoundToFloat](#RoundToFloat)
 -   [RoundToString](#RoundToString)
--   [TruncRound](#TruncRound)
+-   [T运行cRound](#T运行cRound)
 -   [CeilToFloat](#CeilToFloat)
 -   [CeilToString](#CeilToString)
 -   [FloorToFloat](#FloorToFloat)
@@ -54,6 +54,8 @@ import (
 -   [Div](#Div)
 -   [Variance](#Variance)
 -   [StdDev](#StdDev)
+-   [Permutation](#Permutation)
+-   [Combination](#Combination)
 
 <div STYLE="page-break-after: always;"></div>
 
@@ -464,14 +466,14 @@ func main() {
 }
 ```
 
-### <span id="TruncRound">TruncRound</span>
+### <span id="T运行cRound">T运行cRound</span>
 
 <p>截短n位小数（不进行四舍五入）</p>
 
 <b>函数签名:</b>
 
 ```go
-func TruncRound[T constraints.Float | constraints.Integer](x T, n int) T 
+func T运行cRound[T constraints.Float | constraints.Integer](x T, n int) T 
 ```
 
 <b>示例:<span style="float:right;display:inline-block;">[运行](https://go.dev/play/p/aumarSHIGzP)</span></b>
@@ -485,9 +487,9 @@ import (
 )
 
 func main() {
-    result1 := mathutil.TruncRound(0.124, 2)
-    result2 := mathutil.TruncRound(0.125, 2)
-    result3 := mathutil.TruncRound(0.125, 3)
+    result1 := mathutil.T运行cRound(0.124, 2)
+    result2 := mathutil.T运行cRound(0.125, 2)
+    result3 := mathutil.T运行cRound(0.125, 3)
 
     fmt.Println(result1)
     fmt.Println(result2)
@@ -1047,8 +1049,8 @@ import (
 
 func main() {
     result1 := mathutil.Log(8, 2)
-    result2 := mathutil.TruncRound(mathutil.Log(5, 2), 2)
-    result3 := mathutil.TruncRound(mathutil.Log(27, 3), 0)
+    result2 := mathutil.T运行cRound(mathutil.Log(5, 2), 2)
+    result3 := mathutil.T运行cRound(mathutil.Log(27, 3), 0)
 
     fmt.Println(result1)
     fmt.Println(result2)
@@ -1209,7 +1211,7 @@ func main() {
 func StdDev[T constraints.Float | constraints.Integer](numbers []T) float64
 ```
 
-<b>示例:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
 
 ```go
 package main
@@ -1220,8 +1222,8 @@ import (
 )
 
 func main() {
-    result1 := mathutil.TruncRound(mathutil.StdDev([]int{1, 2, 3, 4, 5}), 2)
-    result2 := mathutil.TruncRound(mathutil.StdDev([]float64{1.1, 2.2, 3.3, 4.4, 5.5}), 2)
+    result1 := mathutil.T运行cRound(mathutil.StdDev([]int{1, 2, 3, 4, 5}), 2)
+    result2 := mathutil.T运行cRound(mathutil.StdDev([]float64{1.1, 2.2, 3.3, 4.4, 5.5}), 2)
 
     fmt.Println(result1)
     fmt.Println(result2)
@@ -1230,4 +1232,70 @@ func main() {
     // 1.41
     // 1.55
 }
+```
+
+### <span id="Permutation">Permutation</span>
+
+<p>计算排列数（P(n, k)）。</p>
+
+<b>函数签名:</b>
+
+```go
+func Permutation(n, k uint) uint
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Permutation(5, 3)
+    result2 := mathutil.Permutation(5, 5)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 60
+    // 120
+}
+```
+
+### <span id="Combination">Combination</span>
+
+<p>计算组合数（C(n, k)）。</p>
+
+<b>函数签名:</b>
+
+```go
+func Combination(n, k uint) uint
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Combination(5, 3)
+    result2 := mathutil.Combination(5, 5)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 10
+    // 1
+}
 ```

docs/en/api/packages/mathutil.md

@@ -54,6 +54,8 @@ import (
 -   [Div](#Div)
 -   [Variance](#Variance)
 -   [StdDev](#StdDev)
+-   [Permutation](#Permutation)
+-   [Combination](#Combination)
 
 <div STYLE="page-break-after: always;"></div>
 
@@ -1229,4 +1231,70 @@ func main() {
     // 1.41
     // 1.55
 }
+```
+
+### <span id="Permutation">Permutation</span>
+
+<p>Calculates P(n, k).</p>
+
+<b>Signature:</b>
+
+```go
+func Permutation(n, k uint) uint
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Permutation(5, 3)
+	result2 := mathutil.Permutation(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 60
+	// 120
+}
+```
+
+### <span id="Combination">Combination</span>
+
+<p>Calculates C(n, k).</p>
+
+<b>Signature:</b>
+
+```go
+func Combination(n, k uint) uint
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Combination(5, 3)
+	result2 := mathutil.Combination(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 10
+	// 1
+}
 ```

docs/en/sponsor/sponsor.md

@@ -2,7 +2,7 @@
 
 ### Sponsor me
 
-<b>Hello, I am a software developer and have been engaged in development work for 13 years. Love open source software. And be willing to put in the energy for it. I am the creator of project [lancet](https://github.com/duke-git/lancet). Since Lancet was released as open source two years ago, it has been used by more than 1,000 internal and external projects. lancet will always be free for all users. Your support is a powerful encouragement for me to continue my struggle. Thanks! You can use WeChat to scans the following QR code or clicks the following sponsor button to initiate sponsorship.</b>
+<b>Hello, I am a software developer and have been engaged in development work for 15 years. Love open source software. And be willing to put in the energy for it. I am the creator of project [lancet](https://github.com/duke-git/lancet). Since Lancet was released as open source in 2021, it has been used by more than 1700 internal and external projects. lancet will always be free for all users. Your support is a powerful encouragement for me to continue my struggle. Thanks! You can use WeChat to scans the following QR code or clicks the following sponsor button to initiate sponsorship.</b>
 
 <style>
     .sponsor-ctn {

docs/sponsor/sponsor.md

@@ -1,6 +1,6 @@
 ### 赞助
 
-<b>您好，我是一名软件开发者，从事开发工作 13 年。热爱软件开源。并愿意为此付出精力。是开源项目[lancet](https://github.com/duke-git/lancet)的作者。Lancet 自两年前开源发布以来，已有超过 1000 个内外部项目使用。lancet 一直会对所有用户免费。您的支持是对我继续奋斗的有力鼓励。谢谢! 微信扫描以下二维码或点击以下赞助按钮发起赞助。 </b>
+<b>您好，我是一名软件开发者，从事开发工作15年。热爱软件开源。并愿意为此付出精力。是开源项目[lancet](https://github.com/duke-git/lancet)的作者。Lancet自2021年前开源发布以来，已有超过1700个内外部项目使用。lancet一直会对所有用户免费。您的支持是对我继续奋斗的有力鼓励。谢谢! 微信扫描以下二维码或点击以下赞助按钮发起赞助。 </b>
 
 <style>
     .sponsor-ctn {

mathutil/mathutil.go

@@ -44,14 +44,19 @@ func Fibonacci(first, second, n int) int {
 	}
 }
 
-// Factorial calculate x!.
+// Factorial calculate n!.
 // Play: https://go.dev/play/p/tt6LdOK67Nx
-func Factorial(x uint) uint {
-	var f uint = 1
-	for ; x > 1; x-- {
-		f *= x
+func Factorial(n uint) uint {
+	if n == 0 || n == 1 {
+		return 1
 	}
-	return f
+
+	result := uint(1)
+	for i := uint(2); i <= n; i++ {
+		result *= i
+	}
+
+	return result
 }
 
 // Percent calculate the percentage of value to total.
@@ -417,3 +422,30 @@ func Variance[T constraints.Float | constraints.Integer](numbers []T) float64 {
 func StdDev[T constraints.Float | constraints.Integer](numbers []T) float64 {
 	return math.Sqrt(Variance(numbers))
 }
+
+// Permutation calculate P(n, k).
+// Play: todo
+func Permutation(n, k uint) uint {
+	if n < k {
+		return 0
+	}
+
+	nFactorial := Factorial(n)
+	nMinusKFactorial := Factorial(n - k)
+
+	return nFactorial / nMinusKFactorial
+}
+
+// Combination calculate C(n, k).
+// Play: todo
+func Combination(n, k uint) uint {
+	if n < k {
+		return 0
+	}
+
+	nFactorial := Factorial(n)
+	kFactorial := Factorial(k)
+	nMinusKFactorial := Factorial(n - k)
+
+	return nFactorial / (kFactorial * nMinusKFactorial)
+}

mathutil/mathutil_exmaple_test.go

@@ -502,3 +502,27 @@ func ExampleStdDev() {
 	// 1.41
 	// 1.55
 }
+
+func ExamplePermutation() {
+	result1 := Permutation(5, 3)
+	result2 := Permutation(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 60
+	// 120
+}
+
+func ExampleCombination() {
+	result1 := Combination(5, 3)
+	result2 := Combination(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 10
+	// 1
+}

mathutil/mathutil_test.go

@@ -491,3 +491,49 @@ func TestStdDev(t *testing.T) {
 		assert.Equal(tt.expected, TruncRound(StdDev(tt.numbers), 3))
 	}
 }
+
+func TestPermutation(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestPermutation")
+
+	tests := []struct {
+		n        uint
+		k        uint
+		expected uint
+	}{
+		{1, 1, 1},
+		{1, 0, 1},
+		{0, 1, 0},
+		{0, 0, 1},
+		{3, 2, 6},
+		{4, 2, 12},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(tt.expected, Permutation(tt.n, tt.k))
+	}
+}
+
+func TestCombination(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestCombination")
+
+	tests := []struct {
+		n        uint
+		k        uint
+		expected uint
+	}{
+		{1, 1, 1},
+		{1, 0, 1},
+		{0, 1, 0},
+		{0, 0, 1},
+		{3, 2, 3},
+		{4, 2, 6},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(tt.expected, Combination(tt.n, tt.k))
+	}
+}