day4. day5 is weird.

day4/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func numMatching(sliceToEnd []rune) int {
+	// fmt.Println(sliceToEnd)
+	// gets in a slice from a character to the end, returns an int of the matching characters
+	result := 1
+	for i := 1; i < len(sliceToEnd); i++ {
+		if sliceToEnd[i] == sliceToEnd[0] {
+			result += 1
+		} else {
+			break
+		}
+	}
+	// fmt.Println(result)
+	return result
+}
+
+func testNumber(num int) bool {
+	// cast to string to iterate through digits?
+	strNum := strconv.Itoa(num)
+	runesSlice := []rune(strNum)
+
+	duplicate := false
+
+	for i := 0; i < len(runesSlice)-1; {
+		if runesSlice[i] > runesSlice[i+1] {
+			return false
+		}
+
+		matches := numMatching(runesSlice[i:len(runesSlice)])
+		if matches == 2 {
+			duplicate = true
+			i++
+		} else if matches == 1 {
+			i++
+		} else if matches > 2 {
+			i += (matches - 1)
+		}
+	}
+
+	// if the entire for loop passes, return if there was a duplicate or not
+	return duplicate
+}
+
+func main() {
+	start, end := 138307, 654504
+	possibleCombinations := 0
+
+	for i := start; i <= end; i++ {
+		if testNumber(i) {
+			possibleCombinations++
+		}
+	}
+
+	fmt.Println(possibleCombinations)
+	// fmt.Println(testNumber(111122))
+	// fmt.Println(testNumber(123444))
+	// fmt.Println(testNumber(112233))
+}

day5/main.go

@@ -0,0 +1,67 @@
+package main
+
+import "fmt"
+
+func calcValue(input []int, target int, noun int, verb int) bool {
+	// update the 1 and 2 values here
+	input[1] = noun
+	input[2] = verb
+
+	// fmt.Println(input)
+
+	// loop through all "instructions"
+	for i := 0; i < len(input); i += 4 {
+		// check opertor type (1 2 or 99)
+		operator := input[i]
+		// if it's not 99 (don't terminate, and run a calculation)
+		if operator != 99 {
+			// grab the two values to be added or multiplied
+			value1 := input[input[i+1]]
+			value2 := input[input[i+2]]
+
+			// grab the index that will get the new value
+			indexToUpdate := input[i+3]
+
+			// perform calcuation based on operator value
+			if operator == 1 {
+				input[indexToUpdate] = value1 + value2
+			} else if operator == 2 {
+				input[indexToUpdate] = value1 * value2
+			}
+		} else {
+			// if it is 99, break out of this loop
+			break
+		}
+	}
+
+	// if the target value is found, return true
+	if input[0] == target {
+		return true
+	}
+	return false
+}
+
+func main() {
+	// defualt input slice, index 1 and 2 will be replaced
+	input := []int{1, 12, 2, 3, 1, 1, 2, 3, 1, 3, 4, 3, 1, 5, 0, 3, 2, 1, 6, 19, 1, 19, 5, 23, 2, 13, 23, 27, 1, 10, 27, 31, 2, 6, 31, 35, 1, 9, 35, 39, 2, 10, 39, 43, 1, 43, 9, 47, 1, 47, 9, 51, 2, 10, 51, 55, 1, 55, 9, 59, 1, 59, 5, 63, 1, 63, 6, 67, 2, 6, 67, 71, 2, 10, 71, 75, 1, 75, 5, 79, 1, 9, 79, 83, 2, 83, 10, 87, 1, 87, 6, 91, 1, 13, 91, 95, 2, 10, 95, 99, 1, 99, 6, 103, 2, 13, 103, 107, 1, 107, 2, 111, 1, 111, 9, 0, 99, 2, 14, 0, 0}
+
+	// brute force to try all options for nouns and verbs
+outer:
+	for i := 0; i < 100; i++ {
+		for j := 0; j < 100; j++ {
+			// crete a copy of the input slice
+			clone := make([]int, 120)
+			copy(clone, input)
+
+			// if the calcValue function returns true, break out of the loops and print the values to the console
+			if calcValue(clone, 19690720, i, j) == true {
+				// print answers to console (manually add to advent of code)
+				fmt.Println("noun is", i, "verb is", j)
+				fmt.Println("actual result value noun * 10 + verb = ", i*100+j)
+
+				// use labeled outer loop to break out of both for loops
+				break outer
+			}
+		}
+	}
+}