2020 Day 14 Complete

2020-12-14 15:25:01 -06:00
parent 54aa1b1bf1
commit 0e60e19452
5 changed files with 840 additions and 0 deletions
--- a/2020/day14/main.go
+++ b/2020/day14/main.go
@@ -0,0 +1,119 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	fmt.Println("# Day 13")
+	inp := h.StdinToStringSlice()
+	vsn := h.Atoi(h.OptArgNumber(1, "1"))
+	if vsn == 1 {
+		part1(inp)
+	} else {
+		part2(inp)
+	}
+}
+
+func part1(inp []string) {
+	memory := make(map[int]uint)
+	var mask map[int]uint
+	for _, v := range inp {
+		pts := strings.Split(v, " = ")
+		if pts[0] == "mask" {
+			mask = make(map[int]uint)
+			parsemask := pts[1]
+			for k := range parsemask {
+				if parsemask[k] != 'X' {
+					place := (len(parsemask) - k - 1)
+					if parsemask[k] == '0' {
+						mask[place] = 0
+					} else {
+						mask[place] = 1
+					}
+				}
+			}
+		} else {
+			var reg int
+			fmt.Sscanf(pts[0], "mem[%d]", &reg)
+			val := uint(h.Atoi(pts[1]))
+			store := applyMask(val, mask)
+			memory[reg] = store
+		}
+	}
+
+	var res uint
+	for _, v := range memory {
+		res = res + v
+	}
+	fmt.Println("## Part 1")
+	fmt.Println("Sum:", res)
+}
+
+func applyMask(val uint, mask map[int]uint) uint {
+	for k, v := range mask {
+		if v == 0 {
+			val = val &^ (1 << k)
+		} else if v == 1 {
+			val = val | (1 << k)
+		}
+	}
+	return val
+}
+
+func part2(inp []string) {
+	memory := make(map[uint]uint)
+	var mask string
+	for _, v := range inp {
+		pts := strings.Split(v, " = ")
+		if pts[0] == "mask" {
+			mask = pts[1]
+		} else {
+			var reg int
+			fmt.Sscanf(pts[0], "mem[%d]", &reg)
+			val := uint(h.Atoi(pts[1]))
+			stores := []uint{uint(reg)}
+			for k := range mask {
+				bit := len(mask) - k - 1
+				var wrk []uint
+				for i := range stores {
+					switch mask[k] {
+					case '0':
+						wrk = append(wrk, stores[i])
+					case '1':
+						wrk = append(wrk, setBitTo(stores[i], bit, true))
+					case 'X':
+						wrk = append(wrk, floatBit(stores[i], bit)...)
+					}
+				}
+				stores = append([]uint{}, wrk...)
+			}
+			for k := range stores {
+				memory[stores[k]] = val
+			}
+		}
+	}
+	var sum uint
+	for k := range memory {
+		sum = sum + memory[k]
+	}
+	fmt.Println("## Part 2")
+	fmt.Println("Sum:", sum)
+}
+
+func setBitTo(addr uint, pos int, val bool) uint {
+	if val {
+		return addr | (1 << pos)
+	} else {
+		return addr &^ (1 << pos)
+	}
+}
+func floatBit(addr uint, pos int) []uint {
+	var ret []uint
+	ret = append(ret, addr|(1<<pos))
+	ret = append(ret, addr&^(1<<pos))
+	return ret
+}