[Sync Iteration] go/palindrome-products/1

solutions/go/palindrome-products/1/palindrome_products.go

@@ -0,0 +1,56 @@
+package palindrome
+
+import (
+	"errors"
+)
+
+// Define Product type here.
+type Product struct {
+	Value          int
+	Factorizations [][2]int
+}
+
+func Products(fmin, fmax int) (Product, Product, error) {
+	if fmin > fmax {
+		return Product{}, Product{}, errors.New("fmin > fmax")
+	}
+
+	var smallest, biggest *Product
+	for i := fmin; i <= fmax; i++ {
+		for j := i; j <= fmax; j++ {
+			prod := i * j
+			if !isPalindrome(prod) {
+				continue
+			}
+
+			if smallest == nil || prod < smallest.Value {
+				smallest = &Product{Value: prod, Factorizations: [][2]int{{i, j}}}
+			} else if prod == smallest.Value {
+				smallest.Factorizations = append(smallest.Factorizations, [2]int{i, j})
+			}
+
+			if biggest == nil || prod > biggest.Value {
+				biggest = &Product{Value: prod, Factorizations: [][2]int{{i, j}}}
+			} else if prod == biggest.Value {
+				biggest.Factorizations = append(biggest.Factorizations, [2]int{i, j})
+			}
+		}
+	}
+
+	if smallest == nil || biggest == nil {
+		return Product{}, Product{}, errors.New("no palindromes")
+	}
+
+	return *smallest, *biggest, nil
+}
+
+func isPalindrome(n int) bool {
+	orig := n
+	var reversed int
+	for n != 0 {
+		reversed = reversed*10 + n%10
+		n /= 10
+	}
+
+	return orig == reversed
+}