Added GradeCalculator.java: implemented Java console app for score-to…

Beginner/GradeCalculator.java

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+/**
+ * ------------------------------------------------------------
+ * Program Name : GradeCalculator
+ * Author       : Anukalp Pandey
+ * Description  : A simple console application that takes a student's numerical score
+ *                and prints the corresponding letter grade (A, B, C, D, F)
+ *                using if-else if statements.
+ * Complexity   : O(1) - Constant time complexity, since it performs a fixed
+ *                number of comparisons regardless of input size.
+ * ------------------------------------------------------------
+ */
+
+import java.util.Scanner;
+
+public class GradeCalculator {
+
+    public static void main(String[] args) {
+
+        // Using try-with-resources to ensure Scanner is closed automatically
+        try (Scanner sc = new Scanner(System.in)) {
+            System.out.print("Enter student's score (0 - 100): ");
+            int score = sc.nextInt();
+
+            char grade;
+
+            if (score >= 90 && score <= 100) {
+                grade = 'A';
+            } else if (score >= 80) {
+                grade = 'B';
+            } else if (score >= 70) {
+                grade = 'C';
+            } else if (score >= 60) {
+                grade = 'D';
+            } else if (score >= 0) {
+                grade = 'F';
+            } else {
+                System.out.println("Invalid score entered! Please enter between 0 and 100.");
+                return;
+            }
+
+            System.out.println("Grade: " + grade);
+        } catch (Exception e) {
+            System.out.println("Error: Please enter a valid numerical score.");
+        }
+    }
+}