Day 8

input<-read_lines("Day8Sample.txt")


jboxes<-matrix(0,nrow=length(input),ncol=3)
for(i in 1:length(input)){jboxes[i,]<-as.numeric(unlist(str_split(input[i],",")))}

Part 1

Create the kd tree for the junction boxes

So get the list of distances in order for every single pair

alldists<-nn2(jboxes,k=nrow(jboxes))

Find the

smallcircuit<-function(jb,dists,connections){
  shortestdistances<-as.vector(dists$nn.dists[,2])
  currentneighbor<-rep(2,nrow(jb))
  ### 0 is no circuit
  circuit<-rep(0,nrow(jb))
  circuitnumber<-1
  connectorcount<-0
  while(connectorcount<connections){
    ### which two are the shortest distances
    a<-which(shortestdistances==min(shortestdistances))
    ### update the shortest distance
    ### update the circuit
    currentneighbor[a]<-currentneighbor[a]+1
    shortestdistances[a[1]]<-dists$nn.dists[a[1],currentneighbor[a[1]]]
    shortestdistances[a[2]]<-dists$nn.dists[a[2],currentneighbor[a[2]]]
    ### increment the connector count
    connectorcount<-connectorcount+1
    ### if they're not in the same circuit or both 0 (not circuited yet), update the circuit
    if(circuit[a[1]]!=circuit[a[2]]||(circuit[a[1]]==0&&circuit[a[2]]==0)){
      ### if both 0, make a newcircuit
      if(circuit[a[1]]==0&&circuit[a[2]]==0){
        circuit[a[1]]<-circuitnumber
        circuit[a[2]]<-circuitnumber
        circuitnumber<-circuitnumber+1
        ### if only one is 0, have it join the other circuit
      }else if(circuit[a[1]]==0){
        circuit[a[1]]<-circuit[a[2]]
      }else if(circuit[a[2]]==0){
        circuit[a[2]]<-circuit[a[1]]
        ### otherwise change everything that matches a1 to a2
      }else{
        circuit[which(circuit==circuit[a[1]])]<-circuit[a[2]]}}
  }
  circuit}

p1<-smallcircuit(jboxes,alldists,10)
clumps<-sort(table(p1),decreasing=TRUE)[2:4]
clumps

## p1
## 3 1 4 
## 5 4 2

p1<-prod(clumps)
p1

## [1] 40

Part 2

onebigcircuit<-function(jb,dists){
  shortestdistances<-as.vector(dists$nn.dists[,2])
  currentneighbor<-rep(2,nrow(jb))
  ### 0 is no circuit
  circuit<-rep(0,nrow(jb))
  circuitnumber<-1
  concount<-0
  ### if there's one that isn't 0 and all the rest are equal
  while(any(circuit!=circuit[1])||sum(circuit)==0){
    concount<-concount+1
    ### which two are the shortest distances
    a<-which(shortestdistances==min(shortestdistances))
    ### if they're not in the same circuit or they're both 0
    currentneighbor[a]<-currentneighbor[a]+1
    shortestdistances[a[1]]<-dists$nn.dists[a[1],currentneighbor[a[1]]]
    shortestdistances[a[2]]<-dists$nn.dists[a[2],currentneighbor[a[2]]]

    if(circuit[a[1]]!=circuit[a[2]]||(circuit[a[1]]==0&&circuit[a[2]]==0)){
      ### update the smallest distance
      ### update the circuit
      ### if both 0, make a newcircuit
      if(circuit[a[1]]==0&&circuit[a[2]]==0){
        circuit[a[1]]<-circuitnumber
        circuit[a[2]]<-circuitnumber
        circuitnumber<-circuitnumber+1
        ### if only one is 0, have it join the other circuit
      }else if(circuit[a[1]]==0){
        circuit[a[1]]<-circuit[a[2]]
      }else if(circuit[a[2]]==0){
        circuit[a[2]]<-circuit[a[1]]
        ### otherwise change everything that matches a1 to a2
      }else{
        circuit[which(circuit==circuit[a[1]])]<-circuit[a[2]]}}
  }
  cat(concount,"\n")
  jboxes[a,1]}

p2<-onebigcircuit(jboxes,alldists)

## 29

p2

## [1] 216 117

part2<-prod(p2)
part2

## [1] 25272