add a solution for 238

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/firstthousand/_238.java

@@ -3,6 +3,26 @@
 public class _238 {
 
     public static class Solution1 {
+        public int[] productExceptSelf(int[] nums) {
+            int[] left = new int[nums.length];
+            left[0] = 1;
+            for (int i = 1; i < left.length; i++) {
+                left[i] = nums[i - 1] * left[i - 1];
+            }
+            int[] right = new int[nums.length];
+            right[nums.length - 1] = 1;
+            for (int i = nums.length - 2; i >= 0; i--) {
+                right[i] = nums[i + 1] * right[i + 1];
+            }
+            int[] res = new int[nums.length];
+            for (int i = 0; i < nums.length; i++) {
+                res[i] = left[i] * right[i];
+            }
+            return res;
+        }
+    }
+
+    public static class Solution2 {
         /*
          * Very straightforward idea: iterate through the array twice:
          * first time: get res[i] = res[i-1]*nums[i-1]

src/test/java/com/fishercoder/firstthousand/_238Test.java

@@ -8,13 +8,15 @@
 
 public class _238Test {
     private _238.Solution1 solution1;
+    private _238.Solution2 solution2;
     private static int[] expected;
     private static int[] actual;
     private static int[] nums;
 
     @BeforeEach
     public void setup() {
         solution1 = new _238.Solution1();
+        solution2 = new _238.Solution2();
         expected = new int[] {};
         actual = new int[] {};
     }
@@ -24,6 +26,7 @@ public void test1() {
         nums = new int[] {0, 0};
         expected = new int[] {0, 0};
         actual = solution1.productExceptSelf(nums);
+        actual = solution2.productExceptSelf(nums);
         assertArrayEquals(expected, actual);
     }