refactor 537

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_537.java

@@ -1,6 +1,10 @@
 package com.fishercoder.solutions;
 
+import java.util.stream.Stream;
+
 /**
+ * 537. Complex Number Multiplication
+ *
  * Given two strings representing two complex numbers.
 
  You need to return a string representing their multiplication. Note i2 = -1 according to the definition.
@@ -21,35 +25,49 @@
  */
 public class _537 {
 
-    public String complexNumberMultiply(String a, String b) {
-        String[] part1And2 = a.split("\\+");
-        String[] part3And4 = b.split("\\+");
-        String product1 = String.valueOf(Integer.parseInt(part1And2[0]) * Integer.parseInt(part3And4[0]));//this is real number multiplication
-        String product2 = multiply(part1And2[0], part3And4[1]);
-        String product3 = multiply(part3And4[0], part1And2[1]);
-        String product4 = multiplyTwoIs(part3And4[1], part1And2[1]);
-        String twoISum = sumTwoI(product2, product3);
-        String numberValue = String.valueOf(Integer.valueOf(product1) + Integer.valueOf(product4));
-        return numberValue + "+" + twoISum;
-    }
+    public static class Solution1 {
+        public String complexNumberMultiply(String a, String b) {
+            String[] part1And2 = a.split("\\+");
+            String[] part3And4 = b.split("\\+");
+            String product1 = String.valueOf(Integer.parseInt(part1And2[0]) * Integer.parseInt(part3And4[0]));//this is real number multiplication
+            String product2 = multiply(part1And2[0], part3And4[1]);
+            String product3 = multiply(part3And4[0], part1And2[1]);
+            String product4 = multiplyTwoIs(part3And4[1], part1And2[1]);
+            String twoISum = sumTwoI(product2, product3);
+            String numberValue = String.valueOf(Integer.valueOf(product1) + Integer.valueOf(product4));
+            return numberValue + "+" + twoISum;
+        }
 
-    private String sumTwoI(String product2, String product3) {
-        int number2 = Integer.parseInt(product2.substring(0, product2.length() - 1));
-        int number3 = Integer.parseInt(product3.substring(0, product3.length() - 1));
-        return String.valueOf(number2 + number3) + "i";
-    }
+        private String sumTwoI(String product2, String product3) {
+            int number2 = Integer.parseInt(product2.substring(0, product2.length() - 1));
+            int number3 = Integer.parseInt(product3.substring(0, product3.length() - 1));
+            return String.valueOf(number2 + number3) + "i";
+        }
 
-    private String multiplyTwoIs(String p, String q) {
-        int number1 = Integer.parseInt(p.substring(0, p.length() - 1));
-        int number2 = Integer.parseInt(q.substring(0, q.length() - 1));
-        int numberProduct = number1 * number2;
-        return String.valueOf(-numberProduct);
-    }
+        private String multiplyTwoIs(String p, String q) {
+            int number1 = Integer.parseInt(p.substring(0, p.length() - 1));
+            int number2 = Integer.parseInt(q.substring(0, q.length() - 1));
+            int numberProduct = number1 * number2;
+            return String.valueOf(-numberProduct);
+        }
 
-    private String multiply(String p, String withI) {
-        int numberPart = Integer.parseInt(withI.substring(0, withI.length() - 1));
-        return String.valueOf(numberPart * Integer.valueOf(p)) + "i";
+        private String multiply(String p, String withI) {
+            int numberPart = Integer.parseInt(withI.substring(0, withI.length() - 1));
+            return String.valueOf(numberPart * Integer.valueOf(p)) + "i";
+        }
     }
 
+    public static class Solution2 {
+        /**
+         * (a + bi) * (c + di) could become (ac - bd) + (ad + bc)*i
+         * Thus, we have the following function
+         */
+        public String complexNumberMultiply(String a, String b) {
+            int[] coefficients1 = Stream.of(a.split("\\+|i")).mapToInt(Integer::parseInt).toArray();
+            int[] coefficients2 = Stream.of(b.split("\\+|i")).mapToInt(Integer::parseInt).toArray();
+            return (coefficients1[0] * coefficients2[0] - coefficients1[1] * coefficients2[1]) + "+"
+                    + (coefficients1[0] * coefficients2[1] + coefficients1[1] * coefficients2[0] + "i");
+        }
+    }
 
 }

src/test/java/com/fishercoder/_537Test.java

@@ -11,15 +11,16 @@
  * Created by fishercoder on 1/25/17.
  */
 public class _537Test {
-    private static _537 test;
+    private static _537 .Solution1 solution1;
+    private static _537 .Solution2 solution2;
     private static String expected;
-    private static String actual;
     private static String a;
     private static String b;
 
     @BeforeClass
     public static void setup() {
-        test = new _537();
+        solution1 = new _537.Solution1();
+        solution2 = new _537.Solution2();
     }
 
     @Before
@@ -31,16 +32,15 @@ public void test1() {
         expected = "0+2i";
         a = "1+1i";
         b = "1+1i";
-        actual = test.complexNumberMultiply(a, b);
-        assertEquals(expected, actual);
+        assertEquals(expected, solution1.complexNumberMultiply(a, b));
+        assertEquals(expected, solution2.complexNumberMultiply(a, b));
     }
 
     @Test
     public void test2() {
         expected = "0+-2i";
         a = "1+-1i";
         b = "1+-1i";
-        actual = test.complexNumberMultiply(a, b);
-        assertEquals(expected, actual);
+        assertEquals(expected, solution2.complexNumberMultiply(a, b));
     }
 }