add more

Author: realDuYuanChao

Maths/Factorial.java

@@ -0,0 +1,25 @@
+package Maths;
+
+public class Factorial {
+    public static void main(String[] args) {
+        int n = 5;
+        System.out.println(n + "! = " + factorial(n));
+    }
+
+    /**
+     * Calculate factorial
+     *
+     * @param n the number
+     * @return the factorial of {@code n}
+     */
+    public static long factorial(int n) {
+        if (n < 0) {
+            throw new ArithmeticException("n < 0");
+        }
+        long fac = 1;
+        for (int i = 1; i <= n; ++i) {
+            fac *= i;
+        }
+        return fac;
+    }
+}

Maths/FindMax.java

@@ -0,0 +1,26 @@
+package Maths;
+
+public class FindMax {
+
+    //Driver
+    public static void main(String[] args) {
+        int[] array = {2, 4, 9, 7, 19, 94, 5};
+        System.out.println("max = " + findMax(array));
+    }
+
+    /**
+     * find max of array
+     *
+     * @param array the array contains element
+     * @return max value
+     */
+    public static int findMax(int[] array) {
+        int max = array[0];
+        for (int i = 1; i < array.length; ++i) {
+            if (array[i] > max) {
+                max = array[i];
+            }
+        }
+        return max;
+    }
+}

Maths/FindMin.java

@@ -0,0 +1,26 @@
+package Maths;
+
+public class FindMin {
+
+    //Driver
+    public static void main(String[] args) {
+        int[] array = {2, 4, 9, 7, 19, 94, 5};
+        System.out.println("min = " + findMax(array));
+    }
+
+    /**
+     * find min of array
+     *
+     * @param array the array contains element
+     * @return min value
+     */
+    public static int findMax(int[] array) {
+        int min = array[0];
+        for (int i = 1; i < array.length; ++i) {
+            if (array[i] < min) {
+                min = array[i];
+            }
+        }
+        return min;
+    }
+}

Maths/MaxValue.java

@@ -0,0 +1,24 @@
+package Maths;
+
+public class MaxValue {
+
+    /**
+     * Returns the greater of two {@code int} values. That is, the
+     * result is the argument closer to the value of
+     * {@link Integer#MAX_VALUE}. If the arguments have the same value,
+     * the result is that same value.
+     *
+     * @param a an argument.
+     * @param b another argument.
+     * @return the larger of {@code a} and {@code b}.
+     */
+    public static int max(int a, int b) {
+        return a >= b ? a : b;
+    }
+
+    public static void main(String[] args) {
+        int a = 3;
+        int b = 4;
+        System.out.format("max:%d between %d and %d", max(a, b), a, b);
+    }
+}

Maths/MinValue.java

@@ -0,0 +1,24 @@
+package Maths;
+
+public class MinValue {
+
+    /**
+     * Returns the smaller of two {@code int} values. That is,
+     * the result the argument closer to the value of
+     * {@link Integer#MIN_VALUE}.  If the arguments have the same
+     * value, the result is that same value.
+     *
+     * @param a an argument.
+     * @param b another argument.
+     * @return the smaller of {@code a} and {@code b}.
+     */
+    public static int min(int a, int b) {
+        return a <= b ? a : b;
+    }
+
+    public static void main(String[] args) {
+        int a = 3;
+        int b = 4;
+        System.out.format("min:%d between %d and %d", min(a, b), a, b);
+    }
+}

Maths/PrimeCheck.java

@@ -0,0 +1,31 @@
+package Maths;
+
+import java.util.Scanner;
+
+public class PrimeCheck {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.println("Enter n:");
+        int n = scanner.nextInt();
+        if (isPrime(n)) {
+            System.out.println(n + "is prime number");
+        } else {
+            System.out.println(n + "is not prime number");
+        }
+    }
+
+    /***
+     * Check a number is prime or not
+     * @param n the number
+     * @return {@code true} if {@code n} is prime
+     */
+    public static boolean isPrime(int n) {
+        for (int i = 3; i <= Math.sqrt(n); i += 2) {
+            if (n % i == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+}