advent-of-code/2021/03/second.go

97 lines
1.4 KiB
Go
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2021-12-07 14:26:36 +01:00
package main
import (
"bufio"
"fmt"
"log"
"os"
)
func findBitCount(data []string) []int {
bits := make([]int, 12)
for _, line := range data {
for n := 0; n < 12; n++ {
if line[n] == '1' {
bits[n]++
}
}
}
return bits
}
func main() {
f, err := os.Open("input")
if err != nil {
log.Fatalf("%+v", err)
}
defer f.Close()
scanner := bufio.NewScanner(f)
scanner.Split(bufio.ScanLines)
data := make([]string, 0)
for scanner.Scan() {
data = append(data, scanner.Text())
}
datacsr := make([]string, len(data))
copy(datacsr, data)
var ogr int
for n := 0; n < 12; n++ {
if len(data) == 1 {
break
}
bits := findBitCount(data)
var i byte
if 2*bits[n] >= len(data) {
i = '1'
} else {
i = '0'
}
newdata := make([]string, 0)
for j := 0; j < len(data); j++ {
if data[j][n] == i {
newdata = append(newdata, data[j])
}
}
data = newdata
}
for n := 0; n < 12; n++ {
ogr *= 2
if data[0][n] == '1' {
ogr++
}
}
data = datacsr
var csr int
for n := 0; n < 12; n++ {
if len(data) == 1 {
break
}
bits := findBitCount(data)
var i byte
if 2*bits[n] < len(data) {
i = '1'
} else {
i = '0'
}
newdata := make([]string, 0)
for j := 0; j < len(data); j++ {
if data[j][n] == i {
newdata = append(newdata, data[j])
}
}
data = newdata
}
for n := 0; n < 12; n++ {
csr *= 2
if data[0][n] == '1' {
csr++
}
}
fmt.Println(ogr * csr)
}