brian/adventofcode
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

2017 Day 07 Complete

Browse Source
This commit is contained in:
Brian Buller 2017-12-07 10:08:22 -06:00
parent aa678bf4ff
commit 287c764399
3 changed files with 1598 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

189
2017/day07/day07.go Normal file
View File

@ -0,0 +1,189 @@
package main
import (
"bufio"
"fmt"
"log"
"os"
"strconv"
"strings"
)
type Node struct {
Name string
Parent string
Children []string
Num int
}
// A list of all nodes we've added
var track map[string]*Node
var root *Node
func main() {
track = make(map[string]*Node)
inp := StdinToStrings()
totalWeight := 0
for i := range inp {
n := parseNode(inp[i])
totalWeight += n.Num
updateNodeInTrack(n)
}
fmt.Println("=== Results ===")
n := findRoot()
fmt.Println("Root Node: " + n.Name)
fmt.Println("Total Weight:", totalWeight, "\n")
imb, _ := findImbalance(n.Name)
imbChain := []string{n.Name, imb}
fmt.Println("")
for imb != "" {
fmt.Println("Imbalance on", imb)
imb, _ = findImbalance(imb)
fmt.Println("")
if imb != "" {
imbChain = append(imbChain, imb)
}
}
if len(imbChain) > 2 {
// imbChain[len(imbChain)-3] is the parent
parent := imbChain[len(imbChain)-2]
// imbChain[len(imbChain)-2] should be the one that needs balancing
target := imbChain[len(imbChain)-1]
fmt.Println("Balance At:", target)
_, propWeight := findImbalance(parent)
currWeight := getWeight(target)
fmt.Println("\nAdjust weight of", target, "to:", (track[target].Num + (propWeight - currWeight)))
} else {
fmt.Println("Couldn't find an imbalance")
}
}
// findImbalance returns the wrongly balanced node name
// along with the weight that it _should_ be
func findImbalance(nm string) (string, int) {
fmt.Println(nm, ">>")
weightTracker := make(map[int]int)
chldWeights := getChildWeights(nm)
for k, v := range chldWeights {
fmt.Println(" ", k, " (", track[k].Num, ") :", v)
weightTracker[v]++
}
// Now find the different one
var properWeight int
var wrongNode string
for k, v := range weightTracker {
if v == 1 {
for chK, chV := range chldWeights {
if chV == k {
wrongNode = chK
}
}
} else {
properWeight = k
}
}
return wrongNode, properWeight
}
func getChildWeights(nm string) map[string]int {
ret := make(map[string]int)
for k := range track {
if strings.HasSuffix(getLineage(k), nm+" < "+k) {
ret[k] = getWeight(k)
}
}
return ret
}
func getWeight(nm string) int {
var weight int
for i := range track {
if strings.Contains(getLineage(i), nm+" <") {
weight += track[i].Num
}
}
return weight + track[nm].Num
}
func getLineage(nm string) string {
ret := ""
if i, ok := track[nm]; ok {
ret = getLineage(i.Parent) + " < " + nm
}
return ret
}
func findRoot() *Node {
for i := range track {
if track[i].Parent == "" {
return track[i]
}
}
return nil
}
func updateNodeInTrack(n *Node) *Node {
if _, ok := track[n.Name]; !ok {
// We need to add it
track[n.Name] = n
}
// Now update all child nodes already on the track with this as their parent
for j := range n.Children {
updateNodeInTrack(&Node{Name: n.Children[j], Parent: n.Name})
}
// Now update the other values, if we've got 'em
if n.Num > 0 {
track[n.Name].Num = n.Num
}
if n.Parent != "" {
track[n.Name].Parent = n.Parent
}
return track[n.Name]
}
func parseNode(inp string) *Node {
n := new(Node)
pts := strings.Split(inp, " ")
for i := range pts {
switch i {
case 0:
n.Name = pts[i]
case 1:
n.Num = Atoi(pts[i][1 : len(pts[i])-1])
case 2: // The arrow
continue
default: // All children
childName := pts[i]
if strings.HasSuffix(childName, ",") {
childName = childName[:len(childName)-1]
}
n.Children = append(n.Children, childName)
}
}
return n
}
func StdinToStrings() []string {
var input []string
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
input = append(input, scanner.Text())
}
return input
}
func Atoi(i string) int {
var ret int
var err error
if ret, err = strconv.Atoi(i); err != nil {
log.Fatal("Invalid Atoi")
}
return ret
}

1281
2017/day07/input Normal file
View File

File diff suppressed because it is too large Load Diff

128
2017/day07/problem Normal file
View File

@ -0,0 +1,128 @@
Advent of Code
--- Day 7: Recursive Circus ---
Wandering further through the circuits of the computer, you come upon a tower
of programs that have gotten themselves into a bit of trouble. A recursive
algorithm has gotten out of hand, and now they're balanced precariously in a
large tower.
One program at the bottom supports the entire tower. It's holding a large
disc, and on the disc are balanced several more sub-towers. At the bottom of
these sub-towers, standing on the bottom disc, are other programs, each
holding their own disc, and so on. At the very tops of these
sub-sub-sub-...-towers, many programs stand simply keeping the disc below
them balanced but with no disc of their own.
You offer to help, but first you need to understand the structure of these
towers. You ask each program to yell out their name, their weight, and (if
they're holding a disc) the names of the programs immediately above them
balancing on that disc. You write this information down (your puzzle input).
Unfortunately, in their panic, they don't do this in an orderly fashion; by
the time you're done, you're not sure which program gave which information.
For example, if your list is the following:
pbga (66)
xhth (57)
ebii (61)
havc (66)
ktlj (57)
fwft (72) -> ktlj, cntj, xhth
qoyq (66)
padx (45) -> pbga, havc, qoyq
tknk (41) -> ugml, padx, fwft
jptl (61)
ugml (68) -> gyxo, ebii, jptl
gyxo (61)
cntj (57)
...then you would be able to recreate the structure of the towers that looks
like this:
gyxo
/
ugml - ebii
/ \
| jptl
|
| pbga
/ /
tknk --- padx - havc
\ \
| qoyq
|
| ktlj
\ /
fwft - cntj
\
xhth
In this example, tknk is at the bottom of the tower (the bottom program), and
is holding up ugml, padx, and fwft. Those programs are, in turn, holding up
other programs; in this example, none of those programs are holding up any
other programs, and are all the tops of their own towers. (The actual tower
balancing in front of you is much larger.)
Before you're ready to help them, you need to make sure your information is
correct. What is the name of the bottom program?
Your puzzle answer was ___________.
--- Part Two ---
The programs explain the situation: they can't get down. Rather, they could
get down, if they weren't expending all of their energy trying to keep the
tower balanced. Apparently, one program has the wrong weight, and until it's
fixed, they're stuck here.
For any program holding a disc, each program standing on that disc forms a
sub-tower. Each of those sub-towers are supposed to be the same weight, or
the disc itself isn't balanced. The weight of a tower is the sum of the
weights of the programs in that tower.
In the example above, this means that for ugml's disc to be balanced, gyxo,
ebii, and jptl must all have the same weight, and they do: 61.
However, for tknk to be balanced, each of the programs standing on its disc
and all programs above it must each match. This means that the following sums
must all be the same:
* ugml + (gyxo + ebii + jptl) = 68 + (61 + 61 + 61) = 251
* padx + (pbga + havc + qoyq) = 45 + (66 + 66 + 66) = 243
* fwft + (ktlj + cntj + xhth) = 72 + (57 + 57 + 57) = 243
As you can see, tknk's disc is unbalanced: ugml's stack is heavier than the
other two. Even though the nodes above ugml are balanced, ugml itself is too
heavy: it needs to be 8 units lighter for its stack to weigh 243 and keep the
towers balanced. If this change were made, its weight would be 60.
Given that exactly one program is the wrong weight, what would its weight
need to be to balance the entire tower?
Your puzzle answer was ______.
Both parts of this puzzle are complete! They provide two gold stars: **
At this point, you should return to your advent calendar and try another
puzzle.
If you still want to see it, you can get your puzzle input.
References
Visible links
. http://adventofcode.com/
. http://adventofcode.com/2017/about
. http://adventofcode.com/2017/support
. http://adventofcode.com/2017/events
. http://adventofcode.com/2017/settings
. http://adventofcode.com/2017/auth/logout
. http://adventofcode.com/2017
. http://adventofcode.com/2017
. http://adventofcode.com/2017/leaderboard
. http://adventofcode.com/2017/stats
. http://adventofcode.com/2017/sponsors
. http://adventofcode.com/2017/sponsors
. http://adventofcode.com/2017
. http://adventofcode.com/2017/day/7/input