Initial Commit

go/palindrome-products/palindrome/palindrome_products.go

@@ -0,0 +1,91 @@
+package palindrome
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// Product is a palindromic product and all of its
+// factorizations
+type Product struct {
+	Product        int
+	Factorizations [][2]int
+}
+
+func createProduct(fac1, fac2 int) *Product {
+	p := Product{Product: (fac1 * fac2)}
+	p.addFactors(fac1, fac2)
+	return &p
+}
+
+func (p *Product) hasFactors(fac1, fac2 int) bool {
+	for i := 0; i < len(p.Factorizations); i++ {
+		if p.Factorizations[i][0] == fac1 && p.Factorizations[i][1] == fac2 {
+			return true
+		}
+		if p.Factorizations[i][1] == fac1 && p.Factorizations[i][0] == fac2 {
+			return true
+		}
+	}
+	return false
+}
+
+func (p *Product) addFactors(fac1, fac2 int) {
+	if (fac1 * fac2) == p.Product {
+		if !p.hasFactors(fac1, fac2) {
+			p.Factorizations = append(p.Factorizations, [2]int{fac1, fac2})
+		}
+	}
+}
+
+// Products takes a min and a max and finds
+func Products(fmin, fmax int) (Product, Product, error) {
+	if fmin > fmax {
+		return Product{}, Product{}, fmt.Errorf("fmin > fmax")
+	}
+	var pMin, pMax Product
+	var err error
+	var allProducts []Product
+
+	for i := fmin; i <= fmax; i++ {
+		for j := fmin; j <= fmax; j++ {
+			if isPalindrome(strconv.Itoa(i * j)) {
+				var found bool
+				for k := 0; k < len(allProducts); k++ {
+					if allProducts[k].Product == (i * j) {
+						allProducts[k].addFactors(i, j)
+						found = true
+						break
+					}
+				}
+				if !found {
+					allProducts = append(allProducts, *createProduct(i, j))
+				}
+			}
+		}
+	}
+	for i := range allProducts {
+		if allProducts[i].Product > pMax.Product {
+			// is the old pMax the new pMin?
+			if len(pMin.Factorizations) == 0 {
+				pMin = pMax
+			}
+			pMax = allProducts[i]
+		} else {
+			if allProducts[i].Product < pMin.Product {
+				pMin = allProducts[i]
+			}
+		}
+	}
+	fmt.Println(allProducts)
+	return pMin, pMax, err
+}
+
+func isPalindrome(s string) bool {
+	for i := 0; i < (len(s) / 2); i++ {
+		if s[i] != s[len(s)-1-i] {
+			return false
+		}
+	}
+	return true
+}