Added 2 snippets

README.md

@@ -499,6 +499,48 @@ Inspired by [30 seconds of code](https://github.com/Chalarangelo/30-seconds-of-c
 
 ## Math
 
+### Binary To Decimal
+
+```java
+    /**
+     * converts binary to decimal
+     * @param n number
+     */
+    public static void binaryToDecimal(int n) {
+        String s = reverse(Integer.toString(n));
+        int decimal=0;
+
+        for (int i = 0; i < s.length(); i++) {
+            char ch = s.charAt(i);
+            if(ch=='1') {
+                decimal += Math.pow(2, i);
+            }
+        }
+        System.out.println(decimal);
+    }
+```
+
+### Decimal To Binary
+
+```java
+    /**
+     * converts decimal to binary
+     * @param n number
+     */
+    public static void decimalToBinary(int n) {
+        int d;
+        String dec="";
+        while(n!=0) {
+            d = n%2;
+            dec += Integer.toString(d);
+            n /= 2;
+        }
+
+        String binary = reverse(dec);
+        System.out.println(binary);
+    }
+```
+
 ### Fibonacci
 
 ```java

src/main/java/math/Binary2DecimalSnippet.java

@@ -0,0 +1,38 @@
+package math;
+import java.util.Scanner;
+
+/** Binary to Decimal Conversion
+ * Snippet
+ */
+class Binary2Decimal {
+    /**
+     * function to reverse a string
+     * @param str string
+     * @return rev reversed string
+     */
+    public static String reverse(String str) {
+        String rev="";
+        for (int i = str.length()-1; i >= 0; i--) {
+            char ch = str.charAt(i);
+            rev += ch;
+        }
+        return rev;
+    }
+
+    /**
+     * converts binary to decimal
+     * @param n number
+     */
+    public static void binaryToDecimal(int n) {
+        String s = reverse(Integer.toString(n));
+        int decimal=0;
+
+        for (int i = 0; i < s.length(); i++) {
+            char ch = s.charAt(i);
+            if(ch=='1') {
+                decimal += Math.pow(2, i);
+            }
+        }
+        System.out.println(decimal);
+    }
+}

src/main/java/math/Decimal2BinarySnippet.java

@@ -0,0 +1,37 @@
+package math;
+import java.util.Scanner;
+/** Binary to Decimal Conversion
+ * Snippet
+ */
+class Decimal2Binary {
+    /**
+     * reverse a string
+     * @param str string
+     * @return rev reversed string
+     */
+    public static String reverse(String str) {
+        String rev="";
+        for (int i = str.length()-1; i >= 0; i--) {
+            char ch = str.charAt(i);
+            rev += ch;
+        }
+        return rev;
+    }
+
+    /**
+     * converts decimal to binary
+     * @param n number
+     */
+    public static void decimalToBinary(int n) {
+        int d;
+        String dec="";
+        while(n!=0) {
+            d = n%2;
+            dec += Integer.toString(d);
+            n /= 2;
+        }
+
+        String binary = reverse(dec);
+        System.out.println(binary);
+    }
+}

src/test/java/math/Binary2DecimalSnippetTest.java

@@ -0,0 +1,22 @@
+package math;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/*
+ * Tests for 30 Seconds of Java code library
+ *
+ */
+class Binary2DecimalSnippetTest {
+  /**
+   * Tests for {@link Binary2DecimalSnippet#binaryToDecimal(int)}.
+   */
+  @Test
+   void testLcm() {
+    assertEquals(9, Binary2DecimalSnippet.binaryToDecimal(1001));
+    assertEquals(10, Binary2DecimalSnippet.binaryToDecimal(1010));
+    assertEquals(72, Binary2DecimalSnippet.binaryToDecimal(1001000));
+    assertEquals(7, Binary2DecimalSnippet.binaryToDecimal(111));
+  }
+}

src/test/java/math/Decimal2BinarySnippetTest.java

@@ -0,0 +1,22 @@
+package math;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/*
+ * Tests for 30 Seconds of Java code library
+ *
+ */
+class Binary2DecimalSnippetTest {
+  /**
+   * Tests for {@link Decimal2BinarySnippet#decimalToBinary(int)}.
+   */
+  @Test
+   void testLcm() {
+    assertEquals(1001, Decimal2BinarySnippet.decimalToBinary(9));
+    assertEquals(1010, Decimal2BinarySnippet.decimalToBinary(10));
+    assertEquals(1001000, Decimal2BinarySnippet.decimalToBinary(72));
+    assertEquals(111, Decimal2BinarySnippet.decimalToBinary(7));
+  }
+}