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Day 13

(had to sleep on part 2)
Petra Lamborn 11 months ago
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b24c387b42
2 changed files with 37 additions and 0 deletions
  1. 35
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      13.R
  2. 2
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      input13.txt

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13.R View File

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+library(stringr)
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+input <- readLines("input13.txt")
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+v <- as.numeric(input[1])
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+vals <- unlist(str_split(input[2], ","))
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+bnums <- as.numeric(vals[vals != "x"])
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+times <- bnums - (v %% bnums)
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+bindex <- which.min(times)
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+
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+bnums[bindex] * times[bindex]
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+
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+
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+
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+vbt <- which(vals != "x") - 1
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+
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+target.mod <- (bnums - vbt) %% bnums
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+
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+
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+f2 <- sapply(1:bnums[2], function(x) {
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+           c(x*bnums[1], ((x*bnums[1]) %% bnums[2]) == target.mod[2])
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+})
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+
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+val.2 <- f2[1,f2[2,] == 1]
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+
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+
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+tmp.v <- 0
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+sapply(2:length(bnums), function(x) {
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+           ft <- sapply(1:bnums[x], function(y) {
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+                            cand <- tmp.v + y*prod(bnums[1:(x - 1)])
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+                            c(cand, (cand %% bnums[x]) == target.mod[x])
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+    })
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+           tmp.v <<- ft[1, ft[2,] == 1]
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+           tmp.v
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+})
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+
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+print(tmp.v, digits = 15)

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input13.txt View File

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+1000067
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+17,x,x,x,x,x,x,x,x,x,x,37,x,x,x,x,x,439,x,29,x,x,x,x,x,x,x,x,x,x,13,x,x,x,x,x,x,x,x,x,23,x,x,x,x,x,x,x,787,x,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,x,x,19