Added function in Pangram.java (#3703)

* Added function in Pangram.java

Added isPangramIndexOf() function in Pangram.java

* Added Tests for new function

Added Tests for isPangramIndexOf() function

* fixed typo

* changed function name

* changed function name

Co-authored-by: Debasish Biswas <debasishbsws.abc@gmail.com>

src/main/java/com/thealgorithms/strings/Pangram.java

@@ -36,4 +36,23 @@ public class Pangram {
         }
         return true;
     }
+    
+    /**
+     * Checks if a String is Pangram or not by checking if each alhpabet is present or not
+     *
+     * @param s The String to check
+     * @return {@code true} if s is a Pangram, otherwise {@code false}
+     */
+    public static boolean isPangram2(String s) {
+        if (s.length() < 26) {
+            return false;
+        }
+        s = s.toLowerCase(); // Converting s to Lower-Case
+        for (char i = 'a'; i <= 'z'; i++) {
+            if (s.indexOf(i) == -1) {
+                return false; // if any alphabet is not present, return false
+            }
+        }
+        return true;
+    }
 }