might be making a mistake starting 2018...

2019/day04/part1/main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	start, end := 138307, 654504
+	possibleCombinations := 0
+
+	for i := start; i <= end; i++ {
+		digits := makeDigitsSlice(i)
+		if isIncreasing(digits) && hasDuplicate(digits) {
+			possibleCombinations++
+		}
+	}
+
+	fmt.Println(possibleCombinations)
+}
+
+func makeDigitsSlice(num int) []int {
+	result := make([]int, 6)
+	for i := 5; num > 0; i-- {
+		result[i] = num % 10
+		num -= num % 10
+		num /= 10
+	}
+	return result
+}
+
+func isIncreasing(digits []int) bool {
+	for i := 1; i < len(digits); i++ {
+		if digits[i] < digits[i-1] {
+			return false
+		}
+	}
+	return true
+}
+
+func hasDuplicate(digits []int) bool {
+	for i := 1; i < len(digits); i++ {
+		if digits[i-1] == digits[i] {
+			return true
+		}
+	}
+	return false
+}