Day 7 solution

seven/crabs.go

@@ -0,0 +1,70 @@
+package seven
+
+import (
+	"bufio"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type crabs struct {
+	crabs map[int]int
+	count int
+	max   int
+}
+
+func (c *crabs) load(filename string) error {
+	c.crabs = map[int]int{}
+
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		initialPositions := strings.Split(scanner.Text(), ",")
+		for _, n := range initialPositions {
+			position, err := strconv.Atoi(n)
+			if err != nil {
+				return err
+			}
+
+			if position > c.max {
+				c.max = position
+			}
+
+			c.crabs[position]++
+		}
+
+		for _, count := range c.crabs {
+			c.count += count
+		}
+	}
+	return nil
+}
+
+func (c *crabs) align(notConstant bool) (fuel int) {
+	for i := 0; i < c.max; i++ {
+		fuelUsed := 0
+		for k, count := range c.crabs {
+			fuelPerCrab := int(math.Abs(float64(i - k)))
+			
+			if notConstant {
+				for i := fuelPerCrab - 1; i > 0; i-- {
+					fuelPerCrab += i
+				}
+			}
+
+			fuelUsed += fuelPerCrab * count
+		}
+
+		if i == 0 || fuelUsed < fuel {
+			fuel = fuelUsed
+		}
+	}
+
+	return fuel
+}