116 lines
2.7 KiB
Go
116 lines
2.7 KiB
Go
package main
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import (
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"fmt"
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"io/ioutil"
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"regexp"
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"strconv"
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"strings"
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)
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func main() {
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mem := make(map[int64]int64) // The values are 36-bit - using int64s
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memre, _ := regexp.Compile(`mem\[(\d+)\] = (\d+)`) // isn't matching all memory lines?
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maskre, _ := regexp.Compile(`mask = ([01X]+)`)
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d, _ := ioutil.ReadFile("input")
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lines := strings.Split(string(d), "\n")
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var mask string
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for _, l := range lines {
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memMatch := memre.FindStringSubmatch(l)
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maskMatch := maskre.FindStringSubmatch(l)
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if len(memMatch) != 0 {
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addr, _ := strconv.ParseInt(memMatch[1], 10, 64)
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value, _ := strconv.ParseInt(memMatch[2], 10, 64)
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// Applying the bitmask using strings because I'm doing this the stupid way
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valueString := strconv.FormatInt(value, 2) // value as a binary string
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v := ""
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// Pad out to 36 bits
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for i := 36 - len(valueString); i > 0; i-- {
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v = "0" + v
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}
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v = v + valueString
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applied := ""
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for i, _ := range v {
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if mask[i] != byte('X') {
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applied += string(mask[i])
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} else {
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applied += string(v[i])
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}
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}
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av, _ := strconv.ParseInt(applied, 2, 64) // applied
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mem[addr] = av
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} else if len(maskMatch) != 0 {
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mask = maskMatch[1]
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} else {
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}
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}
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var sum int64 = 0
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for _, v := range mem {
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sum += v
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}
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fmt.Println("Part 1:", sum)
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// Part 2
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mem = make(map[int64]int64) // reset memory
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mask = ""
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for _, l := range lines {
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memMatch := memre.FindStringSubmatch(l)
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maskMatch := maskre.FindStringSubmatch(l)
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if len(memMatch) != 0 {
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addr, _ := strconv.ParseInt(memMatch[1], 10, 64)
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value, _ := strconv.ParseInt(memMatch[2], 10, 64)
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addrString := strconv.FormatInt(addr, 2) // addr as a binary string
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v := ""
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// Pad out to 36 bits
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for i := 36 - len(addrString); i > 0; i-- {
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v = "0" + v
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}
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v = v + addrString
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applied := ""
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var addresses []string
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for i, _ := range v {
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if mask[i] != byte('0') {
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applied += string(mask[i])
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} else {
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applied += string(v[i])
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}
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}
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addresses = constructAddresses(applied)
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for _, a := range addresses {
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d, _ := strconv.ParseInt(a, 2, 64)
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mem[d] = value
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}
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} else if len(maskMatch) != 0 {
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mask = maskMatch[1]
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} else {
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}
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}
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sum = 0
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for _, v := range mem {
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sum += v
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}
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fmt.Println("Part 2:", sum)
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}
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func constructAddresses(addr string) []string {
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var out []string
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x := false
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for _, c := range addr {
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if c == 'X' {
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x = true
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}
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}
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if x == true {
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ones := constructAddresses(strings.Replace(addr, "X", "1", 1))
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zeroes := constructAddresses(strings.Replace(addr, "X", "0", 1))
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for _, i := range ones {
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out = append(out, i)
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}
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for _, i := range zeroes {
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out = append(out, i)
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}
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return out
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}
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return []string{addr}
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} |