restructure solutions dir

solutions/2/q238/solution.go

@@ -0,0 +1,24 @@
+package q238
+
+func productExceptSelf(nums []int) []int {
+	ret := make([]int, len(nums))
+
+	// from left
+	t := 1
+	for i := range len(nums) - 1 {
+		t *= nums[i]
+		ret[i+1] = t
+	}
+	ret[0] = 1
+
+	// from right
+	t = 1
+	for i := len(nums) - 1; i > 0; i-- {
+		t *= nums[i]
+		ret[i-1] *= t
+	}
+
+	return ret
+}
+
+var _ = productExceptSelf