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61 lines
990 B

package main
import (
"AoC2020/helper"
"errors"
"fmt"
"os"
"sort"
)
func main() {
args := os.Args[1:]
input, err := helper.GetInput(args[0])
if err != nil {
fmt.Println(err)
}
fmt.Println(day1(input))
fmt.Println(day1_part2(input))
}
func day1(numbers []int) int {
goal := 2020
sort.Ints(numbers)
p1 := 0
p2 := len(numbers) - 1
for {
if numbers[p1]+numbers[p2] < goal {
p1++
}
if numbers[p1]+numbers[p2] > goal {
p2--
}
if numbers[p1]+numbers[p2] == goal {
return numbers[p1] * numbers[p2]
}
}
}
func day1_part2(numbers []int) (int, error) {
goal := 2020
sort.Ints(numbers)
for i, number := range numbers {
p1 := i + 1
p2 := len(numbers) - 1 - i
for p1 < p2 {
if numbers[p1]+numbers[p2]+number < goal {
p1++
}
if numbers[p1]+numbers[p2]+number > goal {
p2--
}
if numbers[p1]+numbers[p2]+number == goal {
return numbers[p1] * numbers[p2] * number, nil
}
}
}
return 0, errors.New("No Triplet Found")
}