advent-of-code/2021/07/second.go

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2021-12-08 15:48:36 +01:00
package main
import (
"bufio"
"fmt"
"os"
"strconv"
)
func min(a, b int) int {
if a < b {
return a
} else {
return b
}
}
func abs(a int) int {
if a > 0 {
return a
} else {
return -a
}
}
func splitOnCommas(data []byte, atEOF bool) (advance int, token []byte, err error) {
var ch byte
for advance, ch = range data {
if ch < '0' || ch > '9' {
break
}
}
if advance > 0 {
token = data[0:advance]
advance++ // skip the comma
}
return
}
func main() {
positions := make([]int, 0)
s := bufio.NewScanner(os.Stdin)
s.Split(splitOnCommas)
for s.Scan() {
n, _ := strconv.Atoi(s.Text())
positions = append(positions, n)
}
sum := 0
for _, i := range positions {
sum += i
}
mean := sum / len(positions)
// doing a mean with integers sucks
total := 0
total2 := 0
for _, i := range positions {
diff := abs(i - mean)
total += diff * (diff + 1) / 2
diff = abs(i - mean - 1)
total2 += diff * (diff + 1) / 2
}
fmt.Println(min(total, total2))
}