Merge branch 'main' of ssh://git.bullercodeworks.com:2200/brian/adventofcode

2024/day17/examples

@@ -1,5 +0,0 @@
-Register A: 0
-Register B: 2024
-Register C: 43690
-
-Program: 4,0

2024/day17/main2.bk

@@ -1,78 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"slices"
-	"strconv"
-)
-
-func main() {
-	fmt.Println(day17(1))
-	fmt.Println(day17(2))
-}
-
-func day17(part int) string {
-	a, b, c, program := parseRegisters()
-
-	if part == 1 {
-		// part 1: run program and return comma-separated output
-		return fmt.Sprintln(runProgram(a, b, c, program))
-	}
-
-	// part 2: find lowest value of register A that makes the program output itself
-	a = 0 // the initial value of register A doesnt matter here, so we can reset it
-	for pos := len(program) - 1; pos >= 0; pos-- {
-		a <<= 3 // shift left by 3 bits
-		for !slices.Equal(runProgram(a, b, c, program), program[pos:]) {
-			a++
-		}
-	}
-
-	return strconv.Itoa(a) // return a string since part 1 needs a string
-}
-
-func parseRegisters() (int, int, int, []int) {
-	return 33940147, 0, 0, []int{2, 4, 1, 5, 7, 5, 1, 6, 4, 2, 5, 5, 0, 3, 3, 0}
-}
-
-func runProgram(a, b, c int, program []int) []int {
-	out := make([]int, 0)
-	// for each isntruction pointer
-	for ip := 0; ip < len(program); ip += 2 {
-		opcode, operand := program[ip], program[ip+1]
-		// Process combo operand
-		value := operand
-		switch operand {
-		case 4:
-			value = a
-		case 5:
-			value = b
-		case 6:
-			value = c
-		}
-
-		// Execute instruction
-		switch opcode {
-		case 0: // adv - divide A by 2^value
-			a >>= value
-		case 1: // bxl - XOR B with literal
-			b ^= operand
-		case 2: // bst - set B to value mod 8
-			b = value % 8
-		case 3: // jnz - jump if A is not zero
-			if a != 0 {
-				ip = operand - 2
-			}
-		case 4: // bxc - XOR B with C
-			b ^= c
-		case 5: // out - output value mod 8
-			out = append(out, value%8)
-		case 6: // bdv - divide A by 2^value, store in B
-			b = a >> value
-		case 7: // cdv - divide A by 2^value, store in C
-			c = a >> value
-		}
-	}
-
-	return out
-}