89 lines
1.5 KiB
Go
89 lines
1.5 KiB
Go
package main
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import (
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"errors"
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"fmt"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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func main() {
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fmt.Println("# Day 9")
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inp := h.StdinToIntSlice()
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rogue, err := FindRogueNumber(inp)
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if err != nil {
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fmt.Println(err.Error())
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return
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}
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answer, err := FindWeakness(rogue, inp)
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if err != nil {
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fmt.Println(err.Error())
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return
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}
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fmt.Println("Answer:", answer)
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}
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func FindRogueNumber(inp []int) (int, error) {
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for k, v := range inp {
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if k >= 25 {
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if !ContainsPairFor(v, inp[k-25:k]) {
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return v, nil
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}
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}
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}
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return -1, errors.New("All numbers fit")
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}
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func ContainsPairFor(target int, inp []int) bool {
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for i := 0; i < len(inp)-1; i++ {
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for k := i + 1; k < len(inp); k++ {
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if inp[i]+inp[k] == target {
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return true
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}
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}
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}
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return false
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}
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func FindWeakness(target int, inp []int) (int, error) {
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for i := 0; i < len(inp)-1; i++ {
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for k := i + 1; k < len(inp); k++ {
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sum := GetSumForRange(inp[i:k])
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if sum == target {
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return FindSmallest(inp[i:k]) + FindLargest(inp[i:k]), nil
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} else if sum > target {
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break
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}
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}
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}
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return -1, errors.New("No weakness found")
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}
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func GetSumForRange(inp []int) int {
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var ret int
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for k := range inp {
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ret = ret + inp[k]
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}
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return ret
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}
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func FindSmallest(inp []int) int {
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ret := inp[0]
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for k := range inp {
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if inp[k] < ret {
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ret = inp[k]
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}
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}
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return ret
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}
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func FindLargest(inp []int) int {
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ret := inp[0]
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for k := range inp {
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if inp[k] > ret {
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ret = inp[k]
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}
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}
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return ret
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}
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