33: digit cancelling fractions

33_digit_cancelling_fractions/main.go

@@ -0,0 +1,34 @@
+package main
+
+import "fmt"
+
+func main() {
+	solution()
+}
+
+func solution() {
+	dp := 1
+	np := 1
+	for c := 1; c <= 9; c++ {
+		for d := 1; d < c; d++ {
+			for n := 1; n < d; n++ {
+				if (n*10+c)*d == (c*10+d)*n {
+					fmt.Println("d:", d, "n:", n)
+					dp *= d
+					np *= n
+				}
+			}
+		}
+	}
+	fmt.Println("np:", np, "dp:", dp)
+	fmt.Println("num:", dp/findGCD(np, dp))
+}
+
+func findGCD(a, b int) int {
+	for a > 0 {
+		t := a
+		a = b % a
+		b = t
+	}
+	return b
+}

33_digit_cancelling_fractions/main_test.go

@@ -0,0 +1,43 @@
+package main
+
+import "testing"
+
+func Test_findGCD(t *testing.T) {
+	type args struct {
+		a int
+		b int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			"4, 8",
+			args{4, 8},
+			4,
+		},
+		{
+			"12, 48",
+			args{12, 48},
+			12,
+		},
+		{
+			"12, 48",
+			args{12, 48},
+			12,
+		},
+		{
+			"319, 377",
+			args{319, 377},
+			29,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := findGCD(tt.args.a, tt.args.b); got != tt.want {
+				t.Errorf("findGCD() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}