Add LongDivision (#3691)

DIRECTORY.md

@@ -276,6 +276,7 @@
             * [LeonardoNumber](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/LeonardoNumber.java)
             * [LinearDiophantineEquationsSolver](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/LinearDiophantineEquationsSolver.java)
             * [LiouvilleLambdaFunction](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/LiouvilleLambdaFunction.java)
+            * [LongDivision](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/LongDivision.java)
             * [LucasSeries](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/LucasSeries.java)
             * [MagicSquare](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/MagicSquare.java)
             * [MatrixUtil](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/MatrixUtil.java)
@@ -567,11 +568,13 @@
             * [FindMinTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FindMinTest.java)
             * [GaussianTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/GaussianTest.java)
             * [GCDTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/GCDTest.java)
+            * [HarshadNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/HarshadNumberTest.java)
             * [HeronsFormulaTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/HeronsFormulaTest.java)
             * [JosephusProblemTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/JosephusProblemTest.java)
             * [KaprekarNumbersTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java)
             * [LeastCommonMultipleTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LeastCommonMultipleTest.java)
             * [LiouvilleLambdaFunctionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LiouvilleLambdaFunctionTest.java)
+            * [LongDivisionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/LongDivisionTest.java)
             * [MobiusFunctionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/MobiusFunctionTest.java)
             * [PascalTriangleTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/PascalTriangleTest.java)
             * [PerfectCubeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/PerfectCubeTest.java)

src/main/java/com/thealgorithms/maths/LongDivision.java

@@ -0,0 +1,78 @@
+//        Given two integers dividend and divisor, divide two integers without using multiplication, division, and mod operator.
+//
+//        The integer division should truncate toward zero, which means losing its fractional part. For example, 8.345 would be truncated to 8, 
+//        and -2.7335 would be truncated to -2.
+//        My method used Long Division, here is the source "https://en.wikipedia.org/wiki/Long_division"
+
+package com.thealgorithms.maths;
+
+public class LongDivision {
+public static int divide(int dividend, int divisor) {
+        long new_dividend_1 = dividend;
+        long new_divisor_1 = divisor;
+
+        if (dividend < 0) {
+            new_dividend_1 = new_dividend_1 * -1;
+        }
+        if (divisor < 0) {
+            new_divisor_1 = new_divisor_1 * -1;
+        }
+
+        if (dividend == 0 || new_dividend_1 < new_divisor_1) {
+            return 0;
+        }
+
+        StringBuilder answer = new StringBuilder();
+
+        String dividend_string = "" + new_dividend_1;
+        int last_index = 0;
+
+        String remainder = "";
+
+
+        for (int i = 0; i < dividend_string.length(); i++) {
+            String part_v1 = remainder + "" + dividend_string.substring(last_index, i + 1);
+            long part_1 = Long.parseLong(part_v1);
+            if (part_1 > new_divisor_1) {
+                int quotient = 0;
+                while (part_1 >= new_divisor_1) {
+                    part_1 = part_1 - new_divisor_1;
+                    quotient++;
+                }
+                answer.append(quotient);
+            } else if (part_1 == new_divisor_1) {
+                int quotient = 0;
+                while (part_1 >= new_divisor_1) {
+                    part_1 = part_1 - new_divisor_1;
+                    quotient++;
+                }
+                answer.append(quotient);
+            } else if (part_1 == 0) {
+                answer.append(0);
+            } else if (part_1 < new_divisor_1) {
+                answer.append(0);
+            }
+            if (!(part_1 == 0)) {
+                remainder = String.valueOf(part_1);
+            }else{
+                remainder = "";
+            }
+
+            last_index++;
+        }
+
+        if ((dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0)) {
+            try {
+                return Integer.parseInt(answer.toString()) * (-1);
+            } catch (NumberFormatException e) {
+                return -2147483648;
+            }
+        }
+        try {
+            return Integer.parseInt(answer.toString());
+        } catch (NumberFormatException e) {
+            return 2147483647;
+        }
+
+    }
+}

src/test/java/com/thealgorithms/maths/LongDivisionTest.java

@@ -0,0 +1,25 @@
+package com.thealgorithms.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class LongDivisionTest {
+	
+    @Test
+    void testOne() {
+        assertEquals(3, LongDivision.divide(10,3));
+    }
+  
+      @Test
+    void testTwo() {
+        assertEquals(-2, LongDivision.divide(7,-3));
+    }
+  
+  
+      @Test
+    void testThree() {
+        assertEquals(10, LongDivision.divide(105,10));
+    }
+	
+}