1 files changed, 65 insertions, 0 deletions
diff --git a/2021/07/second.go b/2021/07/second.go
new file mode 100644
index 0000000..5133f66
--- /dev/null
+++ b/2021/07/second.go
@@ -0,0 +1,65 @@
+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))
+}