AdventOfCode2021/day07/7b/main.go
2021-12-16 19:55:49 +00:00

119 lines
2.2 KiB
Go

package main
import (
"bufio"
"fmt"
"math"
"os"
"strconv"
"strings"
)
func main() {
content := returnContent("../input")
//content := returnContent("../testInput")
crabs := mergeSort(*content, 0, len(*content)-1)
min, max := crabs[0], crabs[len(crabs)-1]
dists := countDists(min, max)
minDist := 100000000000000000
for i := min; i <= max; i++ {
s := 0
failed := false
for _, start := range crabs {
s += dists[int(math.Abs(float64(start-i)))]
if s > minDist {
failed = true
break
}
}
if failed {
continue
}
if s < minDist {
minDist = s
}
}
fmt.Println(minDist)
}
func countDists(min int, max int) map[int]int {
dists := make(map[int]int)
for i := min; i < max; i++ {
temp := 1
s := 0
for j := i; j < max; j++ {
s += temp
temp++
}
dists[max-i] = s
}
return dists
}
func returnContent(path string) *[]int {
//read file and return it as an array of integers
file, err := os.Open(path)
var content []int
if err != nil {
fmt.Println("Unlucky, the file didn't open")
return &content
}
defer file.Close()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
text := strings.Split(scanner.Text(), ",")
for _, v := range text {
num, _ := strconv.Atoi(v)
content = append(content, num)
}
}
return &content
}
//sorting algorithm
func mergeSort(nums []int, start int, end int) []int {
if start == end {
return []int{nums[start]}
}
var mid int = ((end - start) / 2) + start
//Assign values back into Left and right
left := mergeSort(nums, start, mid)
right := mergeSort(nums, mid+1, end)
var combined []int
//Pointers for new array
leftPointer, rightPointer := 0, 0
for leftPointer <= len(left)-1 || rightPointer <= len(right)-1 {
if leftPointer == len(left) {
addValue(&combined, right[rightPointer], &rightPointer)
} else if rightPointer == len(right) {
addValue(&combined, left[leftPointer], &leftPointer)
} else {
if left[leftPointer] <= right[rightPointer] {
addValue(&combined, left[leftPointer], &leftPointer)
} else {
addValue(&combined, right[rightPointer], &rightPointer)
}
}
}
return combined
}
func addValue(nums *[]int, value int, pointer *int) {
*nums = append(*nums, value)
*pointer++
}