merge: Add Pangram program (TheAlgorithms#441)

* Add Pangram program

* Updated Documentation in README.md

Co-authored-by: github-action <${GITHUB_ACTOR}@users.noreply.github.com>

README.md

@@ -566,6 +566,16 @@ Read our [Contribution Guidelines](CONTRIBUTING.md) before you contribute.
 
 1. [`IsPalindrome`](./strings/palindrome/ispalindrome.go#L26): No description provided.
 
+---
+</details><details>
+	<summary> <strong> pangram </strong> </summary>	
+
+---
+
+##### Functions:
+
+1. [`IsPangram`](./strings/pangram/ispangram.go#L21): No description provided.
+
 ---
 </details><details>
 	<summary> <strong> pascal </strong> </summary>	

strings/pangram/ispangram.go

@@ -0,0 +1,31 @@
+// ispangram.go
+// description: Checks if a given string is pangram or not
+// details: A pangram is a sentence or expression that uses all the letters of the alphabet.
+// Reference: https://www.geeksforgeeks.org/pangram-checking/
+// Author : Kavitha J
+
+package pangram
+
+import (
+	"regexp"
+	"strings"
+)
+
+func cleanString(text string) string {
+	cleanText := strings.ToLower(text)                      // Convert to lowercase
+	cleanText = strings.Join(strings.Fields(cleanText), "") // Remove spaces
+	regex, _ := regexp.Compile(`[^\p{L}\p{N} ]+`)           // Regular expression for alphanumeric only characters
+	return regex.ReplaceAllString(cleanText, "")
+}
+
+func IsPangram(text string) bool {
+	cleanText := cleanString(text)
+	if len(cleanText) < 26 {
+		return false
+	}
+	var data = make(map[rune]bool)
+	for _, i := range cleanText {
+		data[i] = true
+	}
+	return len(data) == 26
+}

strings/pangram/ispangram_test.go

@@ -0,0 +1,53 @@
+package pangram
+
+import (
+	"testing"
+)
+
+var testCases = []struct {
+	name     string // test description
+	input    string // user input
+	expected bool   // expected return
+}{
+	{
+		"empty string",
+		"",
+		false,
+	},
+	{
+		"non pangram string without spaces",
+		"abc",
+		false,
+	},
+	{
+		"non pangram string with spaces",
+		"Hello World",
+		false,
+	},
+	{
+		"Pangram string 1",
+		" Abcdefghijklmnopqrstuvwxyz",
+		true,
+	},
+	{
+		"pangram string 2",
+		"cdefghijklmnopqrstuvwxABC zyb",
+		true,
+	},
+	{
+		"pangram string 3",
+		"The Quick Brown Fox Jumps Over the Lazy Dog",
+		true,
+	},
+}
+
+func TestIsPangram(t *testing.T) {
+	for _, test := range testCases {
+		t.Run(test.name, func(t *testing.T) {
+			func_result := IsPangram(test.input)
+			if test.expected != func_result {
+				t.Errorf("Expected answer '%t' for string '%s' but answer given was %t", test.expected, test.input, func_result)
+			}
+		})
+	}
+}