new

Author: Sbiswas001

out/production/ComputerProject/AlphabeticalSentence.class

@@ -0,0 +1,68 @@
+package com.sbiswas001.twelveproject;
+
+import java.util.Scanner;
+
+/**
+ * This class checks if a number is triangular or not.
+ * A number is triangular if it is formed by the addition
+ * of consecutive sequence of integers starting from 1.
+ * @author Sayan Biswas
+ * @version 23.04.2022
+ */
+public class TriangularNumber {
+
+    /**
+     * Stores the number
+     */
+    private int x;
+
+    /**
+     * Initializes instance variables
+     */
+    private TriangularNumber() {
+        x=0;
+    }
+
+    /**
+     * Inputs number from user
+     */
+    private void input() {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter natural number: ");
+        x = Integer.parseInt(sc.next());
+        if(x < 1) {
+            System.out.println("Wrong input! Try again.");
+            input();
+        }
+    }
+
+    /**
+     * This method checks if a number is triangular or not.
+     * A number is triangular if it is formed by the addition
+     * of consecutive sequence of integers starting from 1.
+     * Let x be the sum of n consecutive numbers from 1.
+     * So, x=n*(n+1)/2, where n is a natural number.
+     * Calculating we get, n=-0.5+-(Math.sqrt(1+8*x))/2
+     * If n is a natural number then x is a triangular number.
+     * @return true or false
+     */
+    private boolean triangularCheck() {
+        double n1, n2;
+        n1 = -0.5+(Math.sqrt(1+8*x))/2;
+        n2 = -0.5-(Math.sqrt(1+8*x))/2;
+        return n1 % 1 == 0 || n2 % 1 == 0;
+    }
+
+    /**
+     * Calls other methods
+     * @param args Arguments passed to main method
+     */
+    public static void main(String[] args) {
+        TriangularNumber ob = new TriangularNumber();
+        ob.input();
+        System.out.println(ob.triangularCheck() ?
+                "Number is a triangular number." :
+                "Number is not a triangular number.");
+    }
+
+}